US3651010A - Synthetic polyamide compositions - Google Patents

Abstract

A POLYAMIDE COMPOSITION WHICH CAN BE MELT SPUN OR SHAPED AND, IF NECESSARY DRAWN, WHICH COMPOSITION COMPRISES A CLASS OF PHENOLS WHICH CONFER INCREASED RESISTANCE TO DEFORMATION TO THE PRODUCT.

Description

March 21, 1972 INITIAL MODULUS C. D. COWELL ET AL SYNTHETIC POLYAMIDE COMPOSITIONS Filed June 26, 1968 FIG] INITIAL MODULUS' vs EXTENSIBILITY. COMPARISON OF 6-6 NYLON AND MELT BLEND F 6-6 NYLON/COMPOUND HI,(92/8I,COLD DRAWN YARNS.( BEFORE AND AFTER BOILING) 0 BEFORE BOILING AFTER BOILING I I I I I I so EXTENSIBILITY o) MSLM Patented Mar. 21, 1972 7 Claims ABSTRACT OF THE DISCLOSURE A polyamide composition which can be melt spun or shaped and, if necessary drawn, which composition comprises a class of phenols which confer increased resistance to deformation to the product.

The present invention relates to synthetic polyamide and co-polyamide compositions for making shaped articles such as filaments, bristles, yarns, films and the like having improved resistance to deformation and also to articles made therefrom.

The invention will be described particularly, but not limitatively, with reference to filaments, yarns and fabrics having improved resistance to deformation.

Synthetic polyamides, for instance nylon 6 or nylon 66, have long been used for the manufacture of yarns and fabrics on account of their desirable properties such as good wear resistance and high strength. Such yarns or fabrics normally exhibit a floppy, pliable feel or easy drape and in some cases, such as curtains, this easy deformation or pliability is an advantage. In other cases, particularly in some areas of the garment field, yarns and fabrics are desirable which have more resistance to deformation, than is obtainable with normal nylon yarns and which, at the same time, exhibit the advantages of the good wear resistance and high strength associated with nylon.

One known way to increase the resistance to deformation of the constituent filaments of a nylon fabric, is by tanning. Either the made-up fabric or the yarn used to make it may be treated for this purpose in a bath containing a tanning agent such as tannic acid. Normally, however, the effect so obtained can be relatively easily removed almost completely by hot water or steam unless a further fixing treatment, such as treatment with metallic salts, is performed.

In the preparation of synthetic polyamide or co-polyamide yarns the molten polymer is extruded through holes to form filaments, which filaments are usually then stretched or drawn in order to orientate their constituent molecules and develop their superior properties.

Treatment of undrawn or drawn filaments, or of yarns comprising them in a tanning bath is not only an undesirable extra operation but when such filaments or yarns are in the form of a wound package it is also almost impossible to carry out in a practical manner owing to diificult and uneven penetration of the tanning agent into the package.

It is clearly desirable to be able to melt-spin synthetic polyamide or co-polyamide filaments in the normal manner, which filaments, after subsequent drawing, if necessary, have improved resistance to deformation at room temperatures. It is also desirable that such improved resistance to deformation should not easily be permanently removed to any large extent by hot water or steam treatment.

Resistance to deformation of a filament may refer to resistance to stretching or to bending. Such resistance may be measured for instance in terms of a modulus. The stretch modulus can be defined by the force per unit area to stretch the filament by a given percentage of its original length. The bending modulus or fiexural rigidity can be defined with reference to the couple required to bend a filament of given dimensions through a given angle. With synthetic polyamide or co-polyamide filaments the bending modulus is generally positively related to the stretch modulus and so this latter property alone is usually used to define the general resistance of such a filament to deformation.

The stretch modulus can be measured in terms of any suitable stretch percentage. In this specification We shall cite the 1% nominal modulus, usually called the Initial Modulus. The Initial Modulus is measured for a filament or yarn as follows:

A 50 cm. length of the filament or yarn is stretched at a rate of 10% of its original length per minute on an Instron tester in a room atmosphere at approximately 67% RH. and 72 F. The tension in the yarn changes with the degree of stretching and the two variables, length and tension, are automatically plotted by the machine. The maximum tension-extension gradient at the point where the stretch is approximately 1% is multiplied by and divided by the initial yarn denier and the figure so obtained is called the Initial Modulus.

An object of the present invention is to provide a composition comprising one or more synthetic polyamides or co-polyamides, which compositions can be melt-spun or shaped and if necessary drawn to produce filaments, bn'stles, yarns, films and the like having improved resistance to deformation.

It is, of course, desirable that such filaments, yarns and the like should be capable of being deformed, such as crimped or bulked, by the processes conventionally employed therefor.

The compositions of the present invention may comprise one or more synthetic polyamides or polyamide copolymers of a random or block nature.

Clearly three important desiderata for the polyamide compositions of the present invention are: 1

(1) that they should be stable at elevated temperatures prior to melt-spinning or shaping;

(2) that they should be capable of being melt-spun or shaped and, if necessary, drawn;

(3) that other properties of the articles produced therefrom, such as strength, should be at least satisfactory and preferably improved.

Since many tanning agents, used in aqueous solutions are phenolic compounds, such compounds were considered by applicants for addition to molten polyamides. Furthermore, phenolic compounds are frequently added in very small amounts to molten polyamides in order to reduce oxidative degradation.

However, it is well known that some phenols, when added in appreciable amounts, may give rise to severe gelling of molten polyamides (for instance simple phenol). At the same time, it has been taught that the addition of phenolic compounds to molten polyamides, in amounts up to about 40%, confers increased pliability on the articles made therefrom. Increased pliability is an effect exactly opposite to that desired in the present context.

Applicants have now found, however, that there is a class of phenolic compounds which compounds when admixed with molten polyamides or co-polyamides do not confer increased pliabiilty on the articles made therefrom but, surprisingly, increase their resistance to deformation.

The phenolic compounds concerned in the present invention also have the surprising advantage that mixtures of them with polyamides or co-polyamides in the molten state are sufiiciently thermally stable for normal meltspinning or shaping to be performed, even when such mixtures contain a relatively high proportion of the phenol and articles so produced can be drawn in the conventional manner to produce useful drawn articles having improved resistance to deformation.

The phenolic compounds for use in the present invention are substantially pure, well defined chemical compounds with a characteristic molecular weight, substantially ascertainable from their chemical formula, and are not impure oligomers or mixtures of oligomers or polymers or resins. The phenolic compounds are selected from the group consisting of poly(alkyl) phenols, poly(hydroxyalkaryl) alkanes and poly(hydroxyalkaryl) arylenes. They are further defined as follows:

(a) they contain one or more benzene rings in the molecule,

(b) each benzene ring has not more than one hydroxyl group attached thereto,

(c) at least one benzene ring has a single hydroxyl group attached thereto,

(d) when the molecule contains less than four benzene rings the ring hydrogen atom at one or both ortho positions to each hydroxyl group is substituted by a secondary or tertiary alkyl, including cyclo-alkyl, aryl or aralkyl group.

(e) the compounds should be soluble to an extent of l40 wt. percent in admixture with one or more polyamides or co-polyamides.

The limiting desiderata determining the size and nature of any substituent groups, or the number of benzene rings, in the molecule are the solubility of the compound in the polyamide or co-polyamide and the production of a composition which is sufiiciently thermally stable to be meltspun or shaped, and, if necessary, drawn to produce articles having increased resistance to deformation.

Benzene rings in the phenol molecule may be linked together by any suitable groups or chains, for instance methylene groups or chains, or sulphone or amide links and the like, consistent with the fulfilment of aforesaid desiderata.

One or more such phenolic compounds should be present in the polyamide mixture for the accomplishing of the objects of the present invention, in a total amount between 2 and 20 Hydroxyl Equivalents per hundred Amide Equivalents and preferably between 3 and 10 such equivalents.

By Hydroxyl Equivalent we mean the molecular weight in grams of the phenolic compound divided by the number of hydroxyl groups in the molecule.

By the term hundred tAmide Equivalents we mean the molecular weight in grams of a notional polyamide or copolyamide containing one hundred carbonamide links.

Whilst phenolic compounds having one or two benzene rings in their molecule do exert an effect in increasing resistance to deformation, the preferred phenols contain three or more benzene rings in their molecule.

The present invention therefore provides a composition comprising one or more synthetic polyamides or co-polyamides, which composition can be melt-spun or shaped and if necessary drawn to produce filaments, bristles, yarns, films and the like having improved resistance to deformation and which composition contains a phenol, which is a substantially pure, well defined chemical compound with a characteristic molecular weight, substantially ascertainable from its chemical formula, and is not an impure oligomer or a mixture of oligomers or a polymer or resin, is selected from the group consisting of poly (alkyl) phenols, poly(hydroxyalkaiyl) alkanes and poly (hydroxyalkaryl) arylenes and is further defined as follows:

(a) it contains one or more benzene rings in the molecule,

(b) each benzene ring has not more than one hydroxyl group attached thereto,

(c) at least one benzene ring has a single hydroxyl group attached thereto,

(d) when the molecule contains less than four benzene rings the ring-hydrogen atom at one or both ortho positions to each hydroxyl group is substituted by a secondary or tertiary alkyl, including cyclo-alkyl, aryl or aralkyl group.

(c) it should be soluble to an extent of l40 wt. percent in admixture with one or more polyamides or co-polyamides,

either one or more such phenols being present in an amount between 2 and 20 Hydroxyl Equivalents per hundred amide equivalents, said Hydroxyl Equivalents being defined as the molecular weight in grams of the phenolic compound divided by the number of hydroxyl groups in the molecule, and said Amide Equivalents being defined as the molecular weight in grams of a notional polyamide or co-polyamide containing one hundred carbonamide links.

The phenolic compounds may be added to the polyamide at any stage before melt-spinning or shaping. For instance, they may be added during the manufacture of the polyamide, preferably just before it is cast to make granules for use in melt-spinning. Alternatively, they may be mixed with said granules or added to the molten polyamide in a melt-spinning or shaping apparatus.

Another convenient method of addiiton is to make granules comprising a suitable blend of one or more polyamides or co-polyamides and comprising a high percentage of one or more of said compounds. Such concentrated, pre-blend granules can then be mixed, in suitable proportion, with the polyamides or co-polyamides used for melt spinning or shaping.

Examples of the compounds used to produce compositions according to the present invention are shown in Table l.

The present invention will now be illustrated, but in no Way limited, by the following practical examples:

EXAMPLE -1 Each of the compounds shown in Table l was dissolved in molten nylon 66 by stirring for 15 mius. at 280 C., in a nitrogen atmosphere. The mixtures, containing 4% by weight of the compound, were cooled and the products melt-spun to produce spun yarns comprising ten continuous filaments each of about nine denier. These yarns were then cold drawn and hot drawn under the conditions shown in Table 2. Both the spinning and drawing behaviour were good. The drawn yarns were then immersed in boiling water for 15 mius., dried in air at approximately 67% RH. and 72 F. for 24 hours and their Initial Modulus, Extensibility and Tenacity then measured.

The Tenacity is the breaking load of the yarn, expressed in grams per denier. The Extensibility is the length by which the yarn can be extended before breaking, expressed as a percentage of its original length. The Initial Modulus is as hereinbefore defined. The results obtained are shown in Table 2 as a function of the number of phenolic hydroxyl groups in the molecule of the phenolic additive. It can be seen that none of the compounds added produced any unacceptable change in Extensibility or Tenacity and that in general the Initial Modulus increased with the number of hydroxyl groups in the molecule.

EXAMPLE 2 Polyamide compositions containing various amounts of Compound III (Table l) and prepared as described for Example 1 were melt-spun and drawn to produce yarns which were tested as described hereinbefore. The results obtained are shown in Table 3. It can be seen from these results that the Initial Modulus increases with the amount of additive without any serious change in the other properties. In all cases, of course, even in the absence of additive, boiling reduced the Initial Modulus as well as altering the other properties, but with 10% additive present the Initial Modulus after boiling was as high or almost as high as the value for normal yarn before boiling.

TAB LE 2 (4% of compound in nylon 66) Number of phenolic groups in additive EXAMPLE 3 5 molecule A mixture of 92 parts of Nylon 66 and 8 parts of Com- 1 2 3 4 pound III (Table 1) was prepared as described for Exam- Yam properties after boiling; pie 1 and melt-spun to form yarn. Th1s yarn was cold z g fi g t pe adrawn at different draw ratios to produce yarn of different ?M M8 18.9 2M 25 3 25 2 extensibilities. The relationship between the Initial Mod- 10 gg z fi s p c n 36.7 33.2 30.0 30.6 30.5 plus and Extensibility, for both boiled and unhoiled yarn, Dravtgn d ad-Data's?" M1 1s shown 1n FIG. 1. It can be seen that the modulus- 18(1) i B 21 2 6 O t q ea effect of the additive is present at all the Extenaxtsn sibiiit'gf'oaiijj 25:6 3116 331i 311% iii s b l t es Tenacity, g./d 6. 70 6. 91 7. 6. 33 6. 21

EXAMPLES 4-28 Further polyamide and copolyamide compositions were prepared containing various amounts of various phenols of the present invention. Such compositions were spun and drawn to produce approximately 130 denier 5 filament yarns having extensibilities lying between approximately 30 and 45.

The drawn yarns were bo1led and then" Inltlal Modulus TABLE 3 measured as described hereinbefore. The said compose tions together with their extensibilities and initlal modull OH equwsper 100 CONH e(1111177- are shown in the following Table 4. In general, as yarn is 0 1.3 2.6 3.9 5.4 6.9 drawn to a higher draw ratio its extenslblllty decreases Percent compound In 0 2 4 6 8 and its 1n1t1a1 modulus lncreases. In order to apprec1ate D t the increased moduli of the yarns produced from the comg??? f temperature positions according to the present 1nvent1on as shown in I.M.],3gi/d.:b H Table 4 such moduli should be compared with the modulus g% ffi 1 i g 33.1 4 corresponding to the same extensibility for poly 1P 16 9 16 G 20 1 0 p e or 01 in taming no phenol add1t1ve (e.g. as 1n FIG. 1). After boilingg 2&2 3&6 3H 3.3 28':

Tenacity, g./d.: TABLE 1 Before boiling 6. 04 6 as 6.05 5.80 5. 72 After boiling." 5.01 5 01 5.22 5.01 5.23 No, of Drawn over hotplate at Compound: Chemical name ffi gf-f 1 2,4 dimethyl-G-t-butyl phenol. lgfetforeabciiling- 0.2; 39 48.0 51.3 61.4 62.4 I or 01 mg l. 7 27. 7 24. 3 28. 8 34.5 11 22 -methylene b1s (4 methyl 6t butyl Extensibility percent:

phenol). Before boiling 13.3 12.2 12.2 11.9 11.0 12.9 1111 1,1,3 tri[(2 methyl-4-hydroxy-5t.butyl)- 410 g efig m 25.6 26.1 24.6 26.0 24.2 26.7 phenyl] butane. Before bgiiiling 7.80 7. 59 8.26 7. 30 7.61 7. 46 IV 1,1,5,5 tetra[(2 methyl-4 hydroxy-St.bu- After 5. 5. 88

tyl)phenyl] pentane.

TABLE 4 Additive Concentration Hydroxyl equivs. Properties of drawn per yarn (alter boiling) hundred Polyamide or 00- Percent amide Extensi- Initia Example N0. polyamide Phenolicaddltwe byweight equivs. bility modnlu 4 nylon 66 Dimethyl Bisphenol A (methyl groups ortho to hydroxyl groups) 8 7.7 41 1 d Tetramethyl Bisphenol A (methyl groups ortho to hydroxyl groups) 8 6. 9 38 21 2,2-di (4-hydroxy-3-metl1ylphenyl)-propane 8.0 7. 7 41.1 17. 8 2,2,-di-(4-hydroxy-3,5-d1methyl phenyl)-propane- 8.0 6.9 37.7 21.3 2,2-di-(4-hydroxy-3,5-di1sopropylpheny1) propane 8. 7 5. 5 36. 7 23. 0 1,1,32-tri(4 hydroxy-3,5-d1methyl-phenyl)-butane 6. 3 5. 4 37. 3 31. 9 2,2,5,5-tetra(4-hydroxy-3,5-dimethy1phenyl) -hexane 5. 9 5.0 37. 0 26. 2 1, 4-bis(di(B-tert-butyl-4-hydroxy-2-methyl phenyl) (methy1)benzene 8.3 5. 5 38. 7 24. 8 1,1,3 tri((2methyl-4-hydr0Xy-5-tert butyDphenyl) butane 8 5. 43 38 29 do 0 0 10 do s 5.4 45 13 nylon 11 do 0 0 44 22 rin do s 8.7 44 a2 MXD/nylon 6"--. do 0 0 30 56 do do s 5.9 31 61 Product of reaction between following phenolic acids and diamines Phenolic acid Diamine acid 19 nylon 66 2-hydroxy-p-toluic acid p-phenlyene-diamine 7.7 5.0 41.3 25.4 20 rin do m-phenylenediamine 7.7 5.0 39.7 24.2 21 do do p-Amino cyclo hexylmethane 9. 6 5.0 33.8 28. 0 22 do 3,3-d1(4-hydroxy-phenyDvaleric p-phenylene-diamine 6.7 5.0 31.8 28.4

acid (diphenolic acid). 23 do do m-Phenylcne-diamine 6. 7 5. 0 29. 2 32. 6 24 do do 4,4 diamino-di-phenylmethane. 7. 5 5. 0 34.1 26. 3 25 do do m-Xylylene diamine 6.9 5.0 44.8 27. 2 26 do 3,3d1(4-hydroxy13,5-dlmethy1- p-Pheny1ene diamlne 7.7 5.0 40. 6 25.1

phenyl) -va1erlc acid(tetramethyi-diphenolic acid). 27 do do m-Phenylene diamine 7. 7 5.0 43.1 33. 3 23 do d p-Amino cyclohexylmethane 8. 7 5.0 33.6 24. 1

What we claim is:

1. A thermally, stable fiber-formable composition comprising a synthetic linear, fiber-formable polyamide having improved resistance to deformation containing an amount sufficient to improve said resistance to deformation of a phenol, said phenol being a substantially pure well-defined chemical compound with a characteristic molecular weight substantially ascertainable from its chemical formula, said phenol being selected from the group consisting of poly(alkyl)phenols, poly(hydroxyalkaryl) alkanes, poly(hydroxyalkaryl) arylenes, said phenol being further defined as follows:

(a) it contains one or more benzene rings in the molecule,

(b) at least one benzene ring has a single hydroxyl group attached thereto,

() when the molecule contains less than four benzene rings the ring hydrogen atom at one or both ortho position to each hydroxyl group is substituted by a secondary or tertiary alkyl, including cyclo-alkyl, aryl or aralkyl group,

(d) it is soluble to an extent of 1-40 wt. percent in admixtures with said polyamide,

said phenol being present in said composition in an amount between 2 and hydroxyl equivalents per hundred amide equivalents, said hydroxyl equivalents being defined as the molecular weight in grams of the phenolic compound divided by the number of hydroxyl groups in the molecule, and said amide hundred equivalents being defined as the molecular weight in grams of a notional polyamide or copolyamide containing one hundred carbonamide links.

2. A composition as claimed in claim 1 wherein said amount is between 3 and 10 hydroxyl equivalents per one hundred amide equivalents.

3. A composition as claimed in claim 1 'wherein said polyamide is polyhexamethylene adipamide.

4. A composition as claimed in claim 1 wherein said phenol contains 3 or more benzene rings.

5. The composition of claim 1 wherein said phenol contains 1 to 4 benzene rings which are each substituted by a single hydroxyl group.

6. A composition as claimed in claim 4 wherein said phenol contains 3 or more benzene rings.

7. The composition of claim 5 wherein said phenol contains only one phenol selected from the group consisting of 2,4,6-trialkyl phenol; 2,2-bis alkylene(4,6-dialkyl phenol); 1,1,3-tri[ (2,5-dialkyl-4 hydroxy)phenol]butane; 1,1,5,5- tetra[ (2,5 dialkyl 4-hydr0xy)phenol]pentane; o-dialkyl bis-phenol A; 2,2-di(4-hydroxy-3-alkyl phenyl) propane; 2,2,5 ,5 -tetra (4-hydroxy-3,5-dialkyl phenyl)hexane and 1,4- bis di 5-alkyl-4-hydr0xy-2-alkylphenyl] alkyl) benzene.

References Cited UNITED STATES PATENTS 3,009,900 11/1961 Hansen et al 26045.7 3,445,408 5/1969 Gabris 26045.95 3,086,960 4/1963 Bletso 26045.95 2,996,466 8/1961 Kessler et a1. 26045.95

HOSEA E. TAYLOR, Examiner W. E. PARKER, Assistant Examiner csmmcmt 9F CQRECTQN Patent Not 3,651,010 Dated March 21. 1972 Inventofls) C.D. Cowell et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

IN THE SPECIFICATION Column 4, line 14, "20" should read "10" Column 4, line 43, subsequent to the numeral "66' insert the phrase --or polyhexamethylene adipamide" Table 4 Under heading "Initial Modulus"; "1 should read "18" IN THE CLAIMS Claim 4 should read:

4. A composition as claimed in claim 1 wherein said phenol contains 2 to 6 benzene rings.

' Signed and sealed thisZZnd d OfFAugUSt 1972.

(SEAL) attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSGHALK Attesting Officer Commissioner of Patents

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