IL32296A - Heat stabilized anti-static polyamides - Google Patents

Description

Tensile strength loss on heating is reduced, in polycarbonamides containing between 0.1 and 20.0 weight percent polyalkoxylated triglyceride of a fatty acid containing from 10 to 30 carbon atoms, by adding from 0.01 to 2.0 weight percent of a sterically hindered phenol.

The invention relates to an additive for a polycar-bonamide composition having antistatic and antisoil properties, wherein the additive reduces loss of strength upon heating.

Copending Israeli Appln..30,081 discloses and claims polycarbonamides having greatly improved permanent antistatic properties, produced by incorporating into the molten polymer prior to filament formation from 0.1 to 20.0 weight percent of a polyalkoxylated triglyceride of a saturated fatty acid having from 10 to 30 carbon atoms. The disclosure of the above noted application is incorporated herein by reference. Unfortunately, the resulting antistatic filaments tend to lose tensile strength on exposure to elevated temperatures for short periods of time, such as during heat setting of fabrics formed from the yarn. It has been discovered that this loss in tensile strength can be reduced by the further addition of sterically hindered phenols as more fully set forth below.

Accordingly, a primary object of the invention is to provide additives for reducing strength loss upon heating in polycarbonamides containing polyalkoxylated triglycerides. A further object is to provide methods for incorporating such additives into filaments, and to provide for such filaments which retain a reater ro ortion of their ori inal tensile Other objects of the invention will in part be obvious and will in part appear hereinafter.

The objects of the invention are achieved by blending the hindered phenol, polymer, and triglyceride prior to filament formation, i.e., prior to melt spinning, As more fully set forth in the above noted application, the polymeric substances with which this invention is concerned are synthetic high molecular weight fiber-forming polycarbonamides of the general type characterized by the presence of recurring carbonamide groups as an integral part of the polymer chain, and wherein such groups are separated by at least two carbon atoms. They are further characterized by high melting point, pronounced crystallinity and insolubility in most solvents except mineral acids, formic acid and phenols. Upon hydrolysis with strong mineral acids the polymers revert to the reactants from which they were formed.

The polyamides of this type are usually made by heating either (a) substantially equimolecular proportions of a diamine and dicarboxylic acid or (b) various amino acids and amide-forming derivatives thereof until the material has polymerized to the fiber-forming stage, which stage is not generally reached until the polyamide has an intrinsic viscosity of at least 0*4, the intrinsic viscosity being defined as: in which ^ ^ is the relative viscosity of a dilute solution of the polymer in m-cresol in the same units and at the same melting points and can be cold drawn to form strong highly oriented fibers.

The diamines, dicarboxylic acids and amide-forming derivatives thereof which can be used as reactants to yield the fiber-forming polyaraides are well known in the art. Suitable diamines may be represented by the general formula NH2(CH2)nNH2 in which n is an integer of two or greater, preferably from 2 to 10. Representative examples are ethylene diamine, propylene diamine, tetramethylene diamine, pentylmethylene diamine, hexamethylene diamine, octamethylene diamine, and decamethylene diamine. Suitable dicarboxylic acid reactants are represented by the general formula: H00CRC00H in which R is a divalent hydrocarbon radical having a chain length of at least two carbon atoms. These dicarboxylic acids may be illustrated by sebacic acid octadecanedioic acid, adipic acid, suberic acid, azelaic acid, undecanedioic acid, glutaric acid, pimelic acid, brassylic acid, and tetradecanedioic acid.

In place of the above-noted dicarboyxlic acids and diamines the amide-forming derivatives thereof can be employed to form fiber-forming polymers. Amide-forming derivatives of the diamines include the carbamates ard N-formyl derivative.

Amide-forming derivatives of the dibasic carboyxlic acids comprise the mono- and di-ester, the anhydride, the mono- and di-amide, and the acid halide.

In addition to the above diamines and dicarboxylic may be prepared from certain of the amino acids. The amino acids are represented by the general formula: H N(CH.) COOH 2 Λ, n in which n is an integer of four or more and preferably from 4 to 11. illustrative examples of these amino acids are 6-arainocaproic acid, 7-arainoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, 13-aminotridecanoic acid, and 22-aminobehenic acid. Also the lactams of these amide acids may be used as monomers from which the polyamides of the present invention may be prepared.

In addition to the homopolyamides, copolyamides and terpolyamides are also contemplated and are within the scope of this invention. The copolyamides and terpolyamides are obtained in known manner. That is, mixtures of diamines and dibasic acids are used in forming the co- and ter-polymers, with the diamine being present in substantially eguimolar proportions to the total dibasic acids present during the polymer-forming reaction. The co- and ter-polymeric products may be formed directly from the corresponding monomers, or one or more homo-polymers may be added to the polymerizable reactants, distribution of the desired units entering the products via amide interchange. Formation of the desired diamine salts of the various dibasic acids prior to melt polymerization assist in control of the reaction. The conventional pol amide melt polymerization cycle is suitable.

To the polycarbonamide is added (as the antistatic weight of said polycarbonamide, of a polyalkoxylated triglyceride of a saturated fatty acid having 12 to 30 carbon atoms. These triglycerides may be represented by the formula: wherein a and b are integers from 2 to 26 with the proviso that the sum of a + b is at least 10. E is an alkyleneoxy radical containing 2 to 5 carbon atoms, and x, y and z are integers greater than zero and wherein the sum of x + y + z is equal to a value of between 50 and 500. The polyoxyalkylene portion of the glyceride, i.e., (E) , (E) and (E) should be in the 3 2* molecular weight range between 2,000 and 22,000 and may be ethoxy, propxy, butoxy, or pentoxy. The long chain saturated fatty acids of the triglyceride may have from 12 to about 30 carbon atoms, with 12 to 25 being preferred. A preferable concentration of the modifying agent to be used is from 1.0 to .0 weight percent The polyalkoxylated triglyceride may be added to the polymer-forming reactants at the initial state of the polymerization or during the course of the polymerization. It is pre into filaments, although it may be mixed with polymer flake prior to the melt spinning of the flake.

The long chain saturated fatty acids in the triglyceride may contain from 12 up to about 30 carbon atoms, with 12 to 25 being preferred. Examples of suitable acids are the hydroxy derivatives of lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, cerotic acid, and the like. The hydroxy derivatives of these saturated fatty acids are easily produced by hydroxylating the corresponding unsaturated fatty acid by known methods. If necessary after hydroxylation, any remaining double bonds may be removed by hydrogenation, for example with hydrogen gas. It is important that the triglyceride be free from carbon to carbon unsaturat on. The reason for this is that the unsaturated fatty acid portion is subject to degradation under the conditions to which polyamide fibers are normally subjected.

A preferred antistatic agent in accordance with this invention is the ethoxylated triglyceride of hydroxy stearic acid. One reason for the preference of this compound is that it is readily available as a derivative of castor oil. Castor oil is known to consist of about 88 percent of the glyceride ester of ricinoleic acid, which may be represented by the following formula: O OH H„C - 0 - C —(-CH2-}y CH = CH - CH2 - C 1H - CgH^ When the above glyceryl triricinoleate is polyethoxylated by known methods, it yields a compound of the following structure: wherein x, y, and z are integers as defined above. When the glyceryl triricinoleate is hydrogenated prior to polyethoxyla-tion then the product of the polyethoxylation may be designated polyethoxylated hydrogenated castor oil, or polyethoxylated glyceryl tristearate and would have the structure: This compound is preferred due to its availability and to its ability to be purified to a high degree and thus the discoloration of the polycarbonamide to which it is added is extremely slight.

The amount of alkylene oxide attached to the triglyceride is important to the extent that it must be sufficient to allow for good dispersion in the polymer. It has been found that less than about 50 moles (i.e., about 2,000 m.w.) results in a poorly dispersed modifying agent. About 500 moles (i.e., limit since it is very difficult to alkoxylate the triglyceride with higher molecular weight material.

The modified synthetic linear polyamides as described herein are prepared by procedures well known in the art and commonly employed in the manufacture of unmodified polyamides. That is, the reactants are heated at a temperature of from 180eC. to 300°C, and preferably from 200eC. to 295°C. until the product has sufficiently high molecular weight to exhibit fiber-forming properties. This condition is reached when the polyamide has an intrinsic viscosity of at least 0.4 in accordance with the definition of intrinsic viscosity as given herein above. The reaction can be conducted at superatmospheric, atmospheric or subatmospheric pressure. Often it is desirable, especially in the last stage of the reaction, to employ conditions, e.g., reduced pressure, which will aid in the removal of the reaction by-product. Preferably, the reaction is carried out in the absence of oxygen, e.g., in an atmosphere of nitrogen.

For convenience, when a diamine and dicarboxylic acid are used in the preparation of a polyamide, it is usually desirable that the dicarboxylic acid be introduced into the reaction as a preformed salt, i.e., 'diamine salt. However, this is a matter of convenience only since the dicarboxylic acid and a corresponding molecular quantity of diamine may be in the form of uncombined diacid-diamine when brought into the reaction zone.

The synthetic linear polycarbonamides of this inven amide-forming production conditions. In addition to the afore-described antistatic agents, delusterants, anti-oxidants, plasticizers, viscosity stabilizers, and other like materials may be used in the preparation of the polyamides of this invention.

According to the invention there is blended into the polycarbonamide-triglyceride system from 0.01 and 2.0 weight percent (based on the weight of the polymer) hindered phenolic materials which are satisfied by the following general formula: OH in which at least one of and R2 is selected from the class consisting of a branched C¾ to C alkyl radical (a radical con-taining between 3 and 8 carbon atoms) , an aralkyl radical such as benzyl, and a hydroxyaralkyl radical wherein the hydroxyaryl portion contains as a substituent a branched C_ to C_ alkyl J o group attached ortho to the hydroxy group. The preferred hydroxyaralkyl radical is a 3-tert-butyl-2-hydroxybenzyl group, although the hydroxy group can be in the 3 or 4 positions if desired. Although the other of R^ and R2 can be hydrogen, methyl or ethyl, preferably both of ^ and R2 are selected from the class noted above.

R3' R4 an<3 R5 can be hydrogen* alkyl, or other sub-stituents which are chemically inert to the extruded composi radical (whether or not a phenolic hydroxy group is included therein) can likewise contain such inert further substituents.

The phenols are preferably melted and blended into the polyalkoxylated triglyceride, which is then blended into the molten polycarbonamide just prior to spinning. However, they can be added to the materials which will be reacted to form the polymer, or can be coated onto polymer flake which is to be melted and extruded, or can be separately blended into the molten polymer before or after blending in the poly-alkoxylated triglyceride.

EXAMPLE I This example illustrates the preparation of filaments of the static resistant polyamide dislcosed in the above-noted copending application, namely, polyhexamethylene adipate (nylon 66) polyblended with 200 molar polyethoxylated hydrogenated castor oil. These yarns will be used as standard of comparison for strength retention properties with polyamides of the same type modified in accordance with this invention.

The following materials are added to a stainless steel high pressure autoclave equipped with a mechanical stirrer: 150 parts of hexamethylene diammonium adipate, 50 parts of water, 50 ppra of manganese added in the form of man-ganous hypophosphite monohydrate salt, and 10.0 weight percent (based on the weight of unmodified polyamide) of hydrogenated castor oil polyethoxylated with 200 moles of ethylene oxide per mole of the glyceride. The autoclave is then purged of air using purified nitrogen and, while stirring, the tempera 200°C. are reached. At this point 2.0 weight percent (based on the weight of unmodified polyamide) of titanium dioxide is added. Next the temperature and pressure in the autoclave are raised until 220°C. at 250 p.s.i.g. (17.577 kg/cm ) pressure are reached. The temperature is then further increased while steam condensate is removed until the temperature reaches 243°C. At this point the pressure is slowly reduced over a 25-minute period to atmospheric pressure while the temperature of the molten polymer is raised to 278°C, at which point the polymer melt is allowed to equilibrate for 30 minutes.

The resultant molten polymer is melt extruded through a 14-hole spinneret to yield white multi ilament yarn. The yarn is drawn 4.43 times its original length and has a tenacity of 5.69 grams per denier at an ultimate elongation of 24.1%. Resistance of this yarn to strength loss upon being exposed to high temperatures is shown in Table I.

EXAMPLE II A batch of polymer is prepared under conditions identical to those employed in Example I, except that 0.05 weight percent (based on the weight of unmodified polymer) of the hindered phenol, 1, 3, 5-trimethyl-2-4-6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene is added to the polymer preparation ingredients. This compound has the following structural formula: This finished polymer is then melt spun through a 14-hole spinneret to yield white filament yarn. The yarn is drawn 4.61 times its original length and has a tenacity of 4.85 grams per denier at an ultimate elongation of 27.5%. Resistance of this yarn to strength loss upon being exposed to high temperatures is shown in Table I and comparison made against control yarn of Example I.

EXAMPLE III Polymer is prepared by employing procedures and techniques identical to those used in Example I, except that 0.5 weight percent (based on the weight of unmodified polymer) of 1,3, 5-trimethy1-2,4, 6-tris(3, 5-di-tert-butyl-4-hydroxybenzyl) benzene is added to the polymer preparation ingredients.

The final polymer thus obtained is melt spun through a 14-hole spinneret to yield a white multi-filament yarn. The yarn is drawn 4.50 times its original length and has a tenacity of 4.67 grams per denier at an ultimate break elongation of 29.0%. Resistance of this yarn to strength loss upon exposure made against control yarn of Example I.

EXAMPLE IV Polymer is prepared by employing procedures and techniques identical to those used in Example I, except that 0.5 weight percent (based on the weight of unmodified polymer) of 4,4'-butylidenebis(6-tert-butyl-m-cresol) is added to the polymer preparation ingredients. This compound has the following formula: The inal polymer thus obtained is melt spun through a 14-hole spinneret to yield a white multifilament yarn. The yarn is drawn 4.55 times its original length and has a tenacity of 4.32 grams per denier at an ultimate break elongation of 28.0%. Resistance of this yarn to strength loss upon exposure to elevated temperatures is shown in Table I and comparison made against control yarn of Example I.

EXAMPLE V Polymer is prepared by employing procedures and techniques identical to those used in Example 1, except that 0.5 weight percent (based on the weight of unmodified polymer) of 2, 2,-methylenebis(4-methyl-6-tert-butyl-phenol) is added to the polymer preparation ingredients.

The final polymer thus obtained is melt spun through yarn is drawn 4.51 tiroes its original length and has a tenacity of 4.23 grams per denier at an ultimate break elongation of 27.1 . Resistance of this yarn to strength loss upon exposure to elevated temperatures is shown in Table I and comparison made against control yarn of Example I.

EXAMPLE VI Polymer is prepared by employing techniques and procedures identical to those employed in Example I, except that 0.1 weight percent (based on the weight of the unmodified poly-mer) of 2,2* -methylene bis (4-methyl-6-tert-butyl phenol) is added to the polymer preparation ingredients.

The final polymer is spun through a 14-hole spinneret to yield a white multifilament yarn. The yarn is drawn 4.51 times its original length and has a tenacity of 4.24 grams per denier and an ultimate break elgonation of 27.1%.

Texting of the yarns prepared in the foregoing examples is conducted by determining the amount of strength loss on elevated temperature exposure.

EXAMPLE VII A batch of polymer is prepared under conditions identical to those employed in Example I, except that 0.1 weight percent (based on the weight of unmodified polymer) of hindered phenolic compound 2,4,6-tris(3-tert-butyl-5-methyl-2-hydroxy-benzyl) phenol is added to the polymer ingredients. The structure of this phenol is as follows: The finished polymer is melt spun through a 14-hole spinneret to yield a white multifilament yarn. The yarn is drawn 4.4 times its original length having a tenacity of 4.80 grams per denier at ultimate break elongation of 30.0%.

Strength retention of this yarn after exposure to 200eC. for 5 minutes is shown in Table I.

TABLE I % Tensile Strength Retained Example After 5 Min. 200°C. Exposure I (control) 47.3 13C (test) 56.7 III (test) 100.0 IV (test) 94.2 V (test) 79.5 VI (test) 52.3 VII (test) 75.0 EXAMPLE VIII This example illustrates the preparation of filaments of static resistant poly- ^-caproamide (nylon 6) polyblended with 200 molar polyethoxylated hydrogenated castor oil. These yarns are used as standard of comparison for heat stability properties with polyaraides of the same type, modified in accord¬ ance with this invention. steel autoclave, equipped with a mechanical stirrers 130 parts of ^-ca rolactam, 5 parts of water, 10 ppra of manganese (added in the form of manganous hypophosphite-monohydrate salt) , and 10.0 weight percent (based on weight of unmodified polyamide) of 200 molar polyethoxylated hydrogenated castor oil (glyceride ester) . The autoclave is then purged of air using purified nitrogen and with stirring, the temperature in the autoclave is slowly raised until values of 190^200eC. are reached. At this point 0.3 weight percent (based on the weight of unmodified polyamide) of titanium dioxide is added.

The temperature and pressure in the autoclave are then raised 2 to 220°C. and 250 p.s.i.g. (17.577 kg/cm ) with removal of steam condensate. Further temperature increase to 243°C. is carried out at which point the pressure is gradually lowered over a 25-minute period to atmospheric pressure while the melt temperature continues to increase to 280eC. The polymer melt is then allowed to equilibrate in the molten state for 30 minutes during which time the temperature is lowered to 240eC.

The resultant molten polymer is melt spun through a 14-hole spinneret to yield white yarn. The yarn is drawn 4.00 times its original length having a tenacity of 5.5 grams per denier at ultimate elongation of 30.0%.

Strength retention of this yarn after exposure to 200°C. for 5 minutes is given in Table II.

EXAMPLE IX This batch of polymer is prepared under the same conditions as described in Example VIII, except that 0.5 weight trimethyl-2,4, 6-tris-(3, 5-di-tert-butyl-4-hydroxybenzyl) benzene is added to the polymer preparation ingredients.

The polymer obtained is melt spun through a 14-hole spinneret to yield white yarn. The yarn is then drawn 4.00 times its original length having a tenacity of 5.7 grams per denier at ultimate elongation of 29.1%.

Strength retention of this yarn after exposure to 200eC. for 5 minutes is related in Table II.

EXAMPLE X Polymer is prepared by employing procedure and techniques identical to those used in Example VIII , except that 0.5 weight percent (based on the weight of unmodified polymer) of 4,4'-butylidenebis-(6-tert-butyl-m-cresol) was added to the polymer ingredients.

The polymer obtained is melt spun through a 14-hole spinneret to yield white yarn. The yarn is then drawn 4.00 times its original length having a tenacity of 5.6 grams per denier at ultimate elongation of 30.0%.

Strength retention of this yarn after exposure to 200eC. for 5 minutes is related in Table II.

TABLE II % Tensile Strength Retained Example After 5 Min. Exposure at 220°C.

VIII (control) 45.0 IX (test) 90.0 X (test) 88.0 Addition of more than 2.0% of the phenol is gradually undesirable because of discoloration of the resulting yarn.

Claims (8)

WHAT WE CLAIM IS:

1. A fiber-forming synthetic linear polycarbon-amide having recurring amide groups as an integral part of the main polymer chain, and wherein said groups are separated by at least two carbon atoms, characterized in that said poly-carbonamide contains: A. from 0.1 to about 20.0 weight percent, based on the weight of said polycarbonamide, of a poly- alkoxylated triglyceride of saturated fatty acid having 10 to 30 carbon atoms, wherein the polyalkoxy portion has a molecular weight of between about 2,000 and 22,000; and B. from 0.01 to 2.0 weight percent of a phenol sterically hindered in the ortho position.

2. The polycarbonamide defined in Claim 1, characterized in that said phenol is devoid of substituents which are chemically active at 200°C. in air for a period of 2 minutes.

3. The polycarbonamide defined in Claim 1, characterized in that the sterically hindering group is selected from the class consisting of branched C^ to Cg alkyl radicals, aralkyl radicals, and hydroxyaralkyl radicals wherein the hydroxyaryl portion contains as a substituent a branched C_ to C alkyl group attached ortho to the hydroxy group.

4. A fiber-forming synthetic linear polycarbonamide as defined in Claim 1, characterized in that said polyalkoxylated glyceride is polyalkoxylated hydrogenated castor oil.

5. A fiber-forming synthetic linear polycarbonamide as defined in Claim 4, characterized in that said polyalkoxy- lated hydrogenated castor oil is present in an amount of from 1.0 to 15.0 weight percent, based on the weight of said polycarbonamide.

6. The fiber-forming synthetic linear polycarbonamide as set forth in Claim 5, characterized in that said polycarbonamide is polyhexamethylene adipamide.

7. The polycarbonamide as defined in Claim 1, characterized by being in the form of a textile fiber.

8. The polycarbonamide as defined in Claim 5, characterized by being in the form of a textile fiber. . I A. E MULPORD Attorney for Applicants