US3123587A

US3123587A - Polyester wash-wear fabric

Info

Publication number: US3123587A
Authority: US
Publication date: 1964-03-03
Anticipated expiration: 1981-03-03

Description

United States Patent 3,123,587 PGLYESTER WAH=WEAR FABRIC Milton J. Hogsed, Kinston, N.C., assign'or to E. I. duPont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Feb. 7, 1961, Ser. No. 87,523 5 Claims. (til. 26075) This invention relates to novel fabrics and to the filaments from which they may be prepared. More particularly, it relates to novel polyester fabrics which exhibit dyeability with a variety of dyes as Well as excellent wash- Wear performance, and tothe filaments from which the fabrics are prepared.

An objective of the textile industry in recent years has been to provide garments made of fabrics which require minimum care. Desirably, such fabrics are relatively free from Wrinkles subsequent to laundering, so that little or no ironing of the fabrics is required. Fabrics which are superior in this regard are frequently described as having good wash-wear performance. It has also been des red, of course, that the fabrics be readily dyeable with a variety of commercially available dyestuffs.

In general, the most satisfactory wash-wear fabrics have been those made of polyester fibers, such as polyethylene terephthalate fibers. It has also been found that, although the unmodified polyester fibers are not especially versatile with respect to the range of suitable dyestuffs and the depth to which the fibers may be dyed, modifications of the polymer by incorporating copolymeric radicals containing sulfonate salt groups results in fibers which are readily dyeable with basic dyes. M0di fication of the polyester fiber in this way is more fully described in British Patent 826,248. Unfortunately, however, it has been observed that fabrics made of polyester fibers modified in this way generally exhibit relatively poor wash-wear behavior. The hydrolytic stability of the fibers is also considerably reduced by incorporating the sulfonate salt modifier units in the polymer. Accordingly, there has been a continuedsearch for a new fiber having the properties required for the production of superior wash-wear fabrics.

It is an object of this invention to provide a readily dyeable fabric having good wash-wear properties. ,7 An other object is to provide such a fabric which exhibits good hydrolytic stability. A further object is to provide fibers from which such fabrics may be prepared. Other objects will become apparent from the following description and claims.

I have found that these objects are accomplished by a boxylic acid, a glycol from the group consisting of ethylene glycol and p-hexahydroxylylene glycol, and from about 1% to about 5% of a copolymeric ester-forming compound containing a sulfonate salt group. Very good wash-wear performance is exhibited by the fabric of the invention. Surprisingly, the fabric is not only dyeable with basic dyes, but its relative dye uptake with disperse dyes is strikingly higher than that obtained with fabrics derived from the corresponding polyester containing no sulfonate salt group copolymeric units. The hydrolytic stability of the fabrics of the invention is quite good.

The term synthetic linear condensation polyester as used herein comprehends a substantially linear polymer of fibenforrning molecular weight comprising a series of predominantly carbon atom chains joined by recurring carbonyloxy radicals,

As used herein, the term polyester is intended to include 7 "ice copolyesters, terpolyesters, and the like. Polyesters having a relative viscosity of at least about 8 are considered to be of fiber-forming molecular weight.

The glycols from which the polyesters are predominantly derived are ethylene glycol, p-hexahydroxylylene glycol, or ester-forming derivatives thereof. The p-hexahydroxylylene glycol may be either the cis-isomer, the transisomer, or mixtures thereof. These glycols may be represented by the formula OH OH CH CH OH CH OH m where m is 0' or 1. Preferably, at least of the hydroxyl radicals in the polyester are derived fromethylene glycol or p-hexahydroxylylene glycol.

In accordance with the invention, the acid component from which the polyester is derived is predominantly a naphthalenedicarboxylic acid; preferably, at least 75% is a naphthalenedicarboxylic acid. In a preferred embodiment of the invention, at least 75% of the acid component of the polyester is a fi,fl'-naphthalenedicarboxylic acid. These acids are characterized by the attachment of one hydroxycarbonyl group to a fi-position (2-or 3-position) of one ring in the naphthalene nucleus and the attachment of the other hydroxycarbonyl group to a p position (6- or 7-position) in the other ring of the naphthalene nucleus. This positioning of the hydroxycarbonyl groups appears to confer excellent properties on polyesters derived from 2,6- or 2,7-naphthalenedicarboxylic acid or ester-forming derivatives thereof.

HOGH2- CH COOH HOOC- 2,6-naphthalenedicarboxylic acid I-IOOO COOH 2,7-naphthalenedicarboxylic acid The term ester-forming group, as used herein, refers to either of the complementary'radicals, hydroxycarbonyl and. hydroxyl which react with the elimination of water to form a carbonyloxy ester radical v ii- The term also includes functional groups equivalent to the hydroxyl group, such as epoxides or esters, particularly the acetate ester or esters of other aliphatic acids having relatively few carbon atoms, as well as. functional groups equivalent to the hydroxycarbonyl group, such as carbonyl halides,.'anhydrides, salts, and esters with the lower alcohols. Similarly, compounds containing esterforming groups are designated as ester-forming com pounds. Of course, each of the complementary hydroxycarbonyl and hydroxyl radicals, or functional groups. derived from them, must be present in the reaction mixture for polycondensation to proceed; and any excess of one of the complementary groups with respect to the other is removed during the reaction, usually by volatilization of compounds containing such groups. Glycol esters (hydroxyalkyl esters) of dicarboxylic acids may function hydrolysis of the carbonyloxy linkages in the polyester chain. A portion of acid component of the polyester may be comprised by the copolymeric ester-forming component containing the sulfonate salt group, if this component is in either capacity as ester-forming compounds and thereby derived from a carboxylic acid. The remainder of the function as intermediates from which polycondensation acid component of the polyester, up to about mol 25%, can be initiated directly. may be any suitable dicarboxylic acid or hydroxycarbox- In accordance with the invention, from about 1 to about ylic acid. Examples of such compounds include tereph- 5% of a copolymeric ester-forming compound containthalic acid, isophthalic acid, 4,4'-sulfonyldibenzoic acid, ing a sulfonate salt group is employed in producing the 1 4,4'-bibenzoic acid, 4,4'-benzophenonedicarboxylic acid, polyester. Such a compound may be represented by 1,2-bis(4 carboxyphenyl)ethane, bis-4-carboxyphenyl the formula ether, 4-(2-hydroxyethyl)benzoic acid, and 4-(2-hydroxy- X RSO M ethoxy)benzoic acid. Where X is an estapforming group as defined above, n r Thelfrlillowgng1 examples are C1t6dtO1lll1Stf1teiht21I1V6n is 1 or 3 R is an Organic radical, and M is a Imtal- Potas 1,, tron, a t oug t ey are not intended to be limitatrve. sium 3,5-dicarbomethoxybenzenesulfonate is an example EXAMPLE 1 of the compound the frlnula in whlcil X ls a Garbo 146 parts of dimethyl 2,6-naphthalenedicarboxylate and methoxy group n 13 R the Lls'tnvalent benzene 3 6 arts of sodium 3 5-dicarbomethox b nzene-sulfonate radical, and M is potassium. In general, any metallic p y are mixed with 115 parts of ethylene glycol contammg element may be employed, examples of spec1fic compounds 0 096 art of man anous acatate and 0 056 a t f anti being the sodium, lithium, calcium, lanthanum, and lead nlon irioxide i mixture i hfi ted 6 2 5 3 salts of 3,5-dicarbomethoxybenzenesulfonic acid. R is a y S mg which tlme the temperature rises from 195 C. to divalent or trivalent organic radical, depending upon the o 4 about 235 C. with evolution of methanol. The pressure value of n, and 1S usually hydrocarbon. However, R

is then reduced to 0.07 mm. of mercury and tne temperamay contam substituents which are mert m the polyester o mm is increased to 285 C. After 2% hours a polymer, reaction mixture. Thus, R may be a halogen-subsututed O1 eth lane 2 6 na hthrdenedicarbox 1ate/5 (sodiu hydrocarbon radical or a chalkogen-containing hydrog zm g hthalaie obtained gi a i carbon radical wherein each chalkogen atom is bonded Oht and a lmlafiv vigcosit 22 3 g to carbon or a difierent chalkogen atom, and no carbon m Com risin'o j of 3 arts hen 7 is bonded to more than one chalkogen atom. Examples s e c a p 0 p 0 an of suitable com ounds include parts of mchlorophenol' P In similar experiments, the corresponding 965/ co- SOdillIH 1,8dwarb0methOXynaphtha1ene-3-S111f0nate, polyester is prepared as well as several control polyesters. Potassium 2,5-dicafbomethofiybeniiiilleSulfollate, The experiments are summarized in Table I. In each Sodium P'CarbOmethoxyballlenesulfonate, 35 case 115 parts of ethylene glycol containing 0.096 part of Sodium III-Garb0melh0XYb$11Zen$l11f0nale, manganous acetate and 0.056 part of antimony trioxide is Potassium 4,4'-diaIb0meth0XYb1Pheny1-2-Su1f0l1ate, used. The properties of the resulting polymers are listed sodium 3-hydroxypropane-l-sulfonate, i th t bl Sodium 4,4-diCa1"beth0XY-l-butanesulfollate, Each of the polyesters listed in Table I is then melted Potassium P'hYdmXYethOXYbenlenesulfonate, 40 and spun into yarn, employing conventional melt-spinning Potassium Z,5"biS(hYdYOXY@thOXY)benleneslllfonate, apparatus. The yarns are wound up at 80 y.p.m. and dithium za y y yy ydrawn 3 X over a hot pin heated to 150. Tests for relaenz n su f tive uptake with disperse dyes and for alkaline sensitivity sodium 2-chloro-3,5-dicarbomethoxybenzenesulfonate, are th i d out for ea h of the yarns. The results and sodium 2-bron1o-3,5-dicarbomethoxybenzenesulfonate. are li t d in the table.

Table I PREPARATION AND PROPERTIES OF POLYESTERS Parts Relative Polymer Disperse Alkaline Starting Starting Parts Viscos- Melting Dye Sensi- Polyester Ester Ester SDBS 3 ity Point, Relative tivity degrees Uptake 1. Polyethylene 2,6-naphthalenedicarboxylate DM 2,6-N 149 none 30 265 0. 5 0.3 2. Polyethylene 2,fi-naphthalenediearboxylate/5- DM 2,6-N 146 3.6 22.3 255 1.2 1.6

(sodium su1fo)-isophthalate (98/2). 3. Polyethylene 2,(i-naphthalenedicarboxylate/d DM 2,6-N 144 6.1 32 250 2.2 2. 7

(sodium sulio)-isophthalate (96.5/3.5). i 4. Polyethylene terephthalate DMT 118 none 30 255 1.0 1. 0' 5. Polyethylene terephthalate/5-(sodium su1fo)- DMT 2 116 3.6 20 250 1.2 10.0

isophthalate (98/2). 6. Polyethylene terephthalate/S-(sodlumsu1fo)- DMT 2 114 6.1 20 245 1.4 27

isophthalate (96.5/3.5).

l Dimethyl 2,6-naphthalenedicarboxylate. 2 Dimethyl terephthalate. 8 Sodium 3,5-diearbomethoxybenzenesulfonate.

R may also contain as inert groups one or more additional SO M groups, an example of such a compound being dipotassiurn S-carbomethoxybenzene 1,3-disulfonate.

The preferred embodiment of the invention comprises a polyester in which at least about 75% of the acid component of the polyester is a naphthalenedicarboxylic acid. By acid component of the polyester is meant the sum The test for relative uptake with disperse dyes is can ried out by boiling one part of the test fabric for 45 minutes in 1000 parts of an aqueous mixture containing 0.4% of a mixture of equal parts of dimethyl terephthalate and benzanil ide and 0.004% of 3-hydroxyquinophthatlone, a yellow disperse dye as disclosed in US. Patent 2,006,022. The dyed fabric is extracted of all the carboxylic acids which would be formed by with chlorobenzene and the amount of dye is estimated spectrophotometrically from the chlorobenzene solution. The results given in Table I are based on assigning an arbitrary value of unity to the amount of dye adsorbed by the polyethylene terephthalate fabric. As indicated in the table, the fabric comprised of polyethylene naphthalenedicai boxylate containing a sulfo-nate salt copolymeric unit has a good level of disperse dyeability, being excellent at 3.5% copolymer level. Fabrics comprised of unmodified polyethylene naphthalenedicarboxyl'ate have a relatively poor level of disperse dyea'bility, while purple.

6 ter at 55 C., and tumbling the fabrics dry in an automatic dryer at 70 C. The fabrics are allowed to hang 1.5 hours and are then evaluated by a group of persons on an arbitrary subjective scale using the following ratrugs:

represents a perfectly flat fabric 4 represents a fabric deviating only slightly from flat 3 represents a fabric acceptable for Wearing Without ironing 10 cfabri'cs comprised of polyethylene terephthalate contain- 2 j f fabri? of bor'defline acceptability for Wearing a sulfonate salt copolymeric unit have a disperse 111g 'Wlthout l easllv touched up dyeability not markedly higher than that of fabric com- 1 P 'P 04333110 unacceptably Yvrinkkd weal'ing prised of unmodified polyethylene terephthalate. Wlthollt Toning, fflthough femiily lrOIled When the fabrics comprised of the polyesters listed in O F P 'F a wIlnkled ri for which considerable Table I are treated for one hour at 100 C. with an aquell'ollmg attentlon is required ous solution of 0.4% of a mixture of equal parts of dimethyl terephthalate and benzanilide and 0.05% of Fuch- T average ratings -f this Y -Y are P rt d Sine SBP dye, a basic dye of they triphenylmethane type in Table II. As noted in the table, tabricscomprrsed'of the tabrics comprised of unmodified polyethylene, terephg polyethlflene naphthalfinedlcflfbofiylflte modified w1th cothalate and unmodified polyethylene naphthalenedicar- Polymeric Sulfonat? Salt units have a Wa h-Wear rating boxylate are essentially undyed. However, each of the Comparable to Tatmgs fabrics of unmodified P 3" fabrics comprised of a polyester containing a sulfonate ethylene terephth-alate. In contrast, fabrics comprised of salt copolyrneric unit is dyed to an excellent shade of poly hylene terephthalate modified with copolymerio sulfonate salt units have a poor wash-wear rating.

Table II PERFORMANCE OF POLYESTER FABRICS Monsanto crease Yarn Weave Wash-wear Weave recovery, percent Polyester fabric count (basket) rating (tafieta) 1. Polyethylene 2,G-naphthalenedicarboxylato/5-(sodium 103/34 102x92 2.3 100x70 61 48 sullo)-isophthalate (97.5/2.5). 2. Polyethylene terephthalate/S-(sodiurn sullo),-isophtha1ate 87/34 104 2:92 0.6 102): 72 47 34 3. riiii iene 2,6-naphtha1enedicarboxylate 104/34 102x80 3.5 103 4 6g 53 4. Polyethylene terephthalate 100/34 106x84 2. 5v 106x82 65 41 The test for alkaline sensitivity is carried out by boiling one part of the test fabric in 1000 parts of a 1% aqueous solution of sodium hydroxide for 3 hours. The results given. in Table I are based on assigning an arbitrary value of unity to the fractional Weight lost by the polyethylene terephthalate fabric. As indicated in the table, modification of polyethylene terephthalate with copolymeric sulfonate salt units results in a very marked increase in the alkaline sensitivity of the fabric. In contrast, fabrics of polyethylene naphthalenedicarboxylate modified with copolymeric sulfonate salt units have a much more acceptable level of alkaline sensitivity, closer to the level observed in fabrics of unmodified polyethylene terephthalate.

EXAMPLE 2 Polyethylene 2,6-naphthalenedicarboxylate/54(sodium sulfo)is0phthalate (97.5/2.5) is prepared in accordance with the method of Example 1, using 45.4 parts of dimethyl 2,6-naphthalenedicarboxylate and 1.4 parts of sodium 3,5-dicarbomethoxyb enzenesulfonate. Polyethylene 2,6-naphthalenedicarboxylate, polyethylene terephthalate, and polyethylene terephthalate/S-(sodium sulfo) isophthalate (98/2) are also prepared as described. Each of the polyesters is then melted and spun into yarn, employing conventional melt-Spinning apparatus. The yarns are wound up at 1200 y.p.m. and drawn 2 over a 175 hot plate.

Basket weave and talfeta fabrics are then prepared from the drawn yarns, and the resulting fabrics. are evaluated [for wash performance and crease recovery in a series of tests for which the results are given in Table ll.

The wash-wear rating of the fabrics is carried out by washing the fabrics in a home model washing machine using water at 55 C. with a commercially available detergent for home laundry use, rinsing the fabric in wa- Monsanto crease recovery values are determined in accordance with Tentative Test Method 66-1959 in the Technical Manual of the American Association of Textile Chemists and Colorists, volume XXXV, Howes Publishing Co@, New York city (1959), pages 171-3. The fabrics are creased while Wet with 40 C. Water in one series of tests and with 60 C. water in a second series of tests. The results for each series of tests, calculated as percent recovery from a standard crease in 120 seconds, are reported in Table ll. As indicated in the table, fabrics comprised of polyethylene naphthalenedicarboxylate modified with copolymeric sulfonate salt units. have 40 C. crease recovery values comparable to values for fabrics of unmodified polyethylene terephthalate, and 60 C. crease value superior to values for fabrics of un modified polyethylene terephthalate. By contrast, fabrics comprised of polyethylene terephthalate modified with copolymeric sulfonate salt units have relatively poor crease recovery values.

EXAMPLE 3 The temperature is increased to 295 C. and the glycol is removed by vacuum distillation at 0.1 mm. for 1.5 hours. After cooling, the polymer is'crushed and theviscosity is increased by solid phase polymerization at 250 C. under vacuum for 3.5 hours. The relative viscosity is 21.5 and part by weight of the fabric is immersed for 90 minutes at the boil in 1000 parts of an aqueous solution of 0.5% of o-phenylphenol and 0.03% of Brilliant Green dye (Color Index No. 42040), a basic dye of the triphenylmethane type, whereupon the fabric is dyed a deep shade of green with good wash-fastness properties. Another sample of the fabric is dyed an attractive shade of yellow with 3'-hydroxyquinophthalone under the dye-bath conditions described in Example I.

Similar results are obtained by repeating the above experiment, substituting 2.2 parts of potassium 2,5-dicarbomethoxybenzenesulfonate for the sodium 3,5-dicarbomethoxybenzenesulfonate. The experiment is repeated again, substituting 4.5 parts of sodium 3-hydroxypropanel-sulfonate for the sodium 3,S-dicarbomethoxybenzenesulfonate, whereupon similar results are obtained.

EXAMPLE 4 131 parts of dimethyl 1,S-naphthalenedicarboxylate and 5.7 parts of sodium 3,S-dicaroomethoxyhenzenesulfonate are mixed with 160 parts of p-hexahydroxylylene glycol (50% cis-, 50% trans-). Four parts of an 8% solution of (n-C H O) TiI-INa in butanol are added and the mixture is heated at 215 C. for 0.75 hour. Methanol is removed in a stream of nitrogen. The temperature is increased to 285 and glycol is removed by distillation at 0.05 mm. for 2.5 hours. The polymer is crushed and the relative viscosity is increased to 23 by solid phase polymerization under vacuum at 250 C. for hours. The polymer melts at 270 C. and yields fibers which are strong and resilient after drawing. Fabrics prepared from the fibers exhibit good wash-wear performance and are readily dyed by Brilliant Green dye and by 3'-hydroxy-- 'quinophthalone under the conditions described in Examples 3 and 1, respectively.

Similar results are obtained by repeating the above experiment, substituting 4.5 parts of sodium m-carbomethoxybenzenesulfonate for the sodium 3,5-dicarbomethoxybenzenesulfonate.

EXAMPLE 5 146 parts of dimethyl 2,6-naphthalenedicarboxylate and 6.4 parts of sodium 3,5-dicarbomethoxybenzenesulfonate are mixed with 180 parts of p-hexahydroxylylene glycol (50% cis-, 50% trans-) and 5 parts of an 8% solution of (n-C H O) TiHNa in butanol. The mixture is heated at 210230 C. for 0.5 hour with evolution of methanol. The temperature is increased to 290 C. and the pressure is reduced to 0.07 mm. Glycol is removed by vacuum distillation at 295 C. for 1.5 hours. The polymer has a relative viscosity of 30.5 and melts at 260 C. It is readily spun into fibers which are strong and resilient after drawing. Fabrics prepared from the fibers exhibit good washwear performance and are readily dyed by Brilliant Green dye and by 3-hydroxyquinophthalone under the conditions described in Examples 3 and 1, respectively.

Similar results are obtained by repeating the above experiment, substituting 6.4 parts of sodium 4,4-dicarhethoxy-l-butanesulfonate for the sodium 3,5-dicarbomethoxybenzenesulfonate.

8 EXAMPLE 6 146 parts of dimethyl 2,7-naphthalenedicarboxylate and 6.4 parts of sodium 3,S-dicarbomethoxybenzenesulfonate are mixed with 180 parts of trans-p-hexahydroxylylene glycol and 5 parts of an 8% solution of (n-C H O) TiHNa in butanol. The mixture is heated for one hour at 215- 225 C. with evolution of methanol. The temperature is increased to 285 C. and the pressure is reduced to 0.05 mm. Glycol is removed by vacuum distillation at 285 C. for 2.5 hours. The polymer is crushed and the relative viscosity is increased to 27 by solid phase polymerization under vacuum at 240 C. for 4 hours. The polymer melts at 260 C. and yields fibers which are strong and resilient after drawing. Fabrics prepared from the fibers exhibit good wash-Wear performance and are readily dyed by Brilliant Green dye and by 3-hydroxyquinophtha1one under the conditions described in Examples 3 and 1, re spectively.

Similar results are obtained by repeating the above experiment, substituting 115 parts of ethylene glycol for the p-hexahydroxylylene glycol.

It will be apparent that many widely different embodiments of this invention may be made without departing from the spirit and scope thereof, and therefore it is not intended to be limited except as indicated in the appended claims.

I claim:

1. A fabric comprised of fibers of a polymeric synthetic linear fiber-forming condensation copolyester of (1) a naphthalenedicarboxylic acid; (2) a glycol selected from the class consisting of ethylene glycol, p-hexahydroxylylene glycol, and their ester-forming derivatives; and (3) from 1% to 5% thereof of a compound having the formula X RsO M in which X is a group selected from the class consisting of carboxyl, hydroxyl and ester-forming derivatives thereof; n is an integer from 1 to 2; R is a group selected from the class consisting of hydrocarbons, halogen substituted hydrocarbons and chalkogen substituted hydrocarbons; said hydrocarbon group being free from aliphatic unsaturation; and M is a metal.

2. The fabric of claim 1' in which at least of the acid component of the polyester is a fi,,l3'-naphthalenedicarboxylic acid.

3. The fabric of claim 2 in which the naphthalenedicarboxylic acid is 2,6-naphthalenedicarboxylic acid.

4. The fabric of claim 2 in which the naphthalenedi carboxylic acid is 2,7-naphthalenedicarboxylic acid.

5. A wash-wear fabric of claim 1 having a wash-wear rating as herein described of greater than 2.

References Cited in the file of this patent UNITED STATES PATENTS 2,910,466 Kibler et a1 Aug. 25, 1959 2,931,068 Kitson et al. Apr. 5, 1960 FOREIGN PATENTS 585,044 Canada Oct. 13, 1959 Disclaimer 3,123,587.-Milton J. Hogsecl, Kinston, N JO. POLYESTER WASH-WEAR FABRIC. Patent dated Mar. 3, 1964. Disclaimer filed Aug. 24;, 1964:, by the assignee, E. I. du Pont de N emow's and UOmpan Hereby enters this disclaimer to claims 1 and 5 of said patent.

[Ofiicial Gazette December 1, 1.964.]

Claims

1. A FABRIC COMPRISED OF FIBERS OF A POLYMERIC SYNTHETIC LINEAR FIBER-FORMING CONDENSATION COPOLESTER OF (1) A NAPHTHALENEDICARBOXYLIC ACID; (2) A GLYCOL SELECTED FROM THE CLASS CONSISTING OF ETHYLENE GLYCOL, P-HEXAHYDROXYLYLENE GLYCOL, AND THEIR ESTER-FORMING DERIVATIVES; AND (3) FROM 1% TO 5% THEREOF OF A COMPOUND HAVING THE FORMULA XNRSO3M IN WHICH X IS A GROUP SELECTED FROM THE CLASS CONSISTING OF CARBOXYL, HYDROXYL AND ESTER-FORMING DERIVATIVES THEREOF; N IS AN INTEGER FROM 1 TO 2; R IS A GROUP SELECTED FROM THE CLASS CONSISTING OF HYDROCARBONS, HALOGEN SUBSTITUTED HYDROCARBONS AND CHALKOGEN SUBSTITUTED HYDROCARBONS; SAID HYDROCARBON GROUP BEING FREE FROM ALIPHATIC UNSATURATION; AND M IS A METAL.