CA1076740A - Polyamides - Google Patents

Abstract

POLYAMIDES

Abstract of the Disclosure Normally solid, moldable polyamides having diamine-derived structural units of the formula wherein each A is individually selected from the group consisting of 5-methyl-nonamethylene, 2,4-diamethyloctamethylene, 2,4,6-trimethylheptamethylene, and 4-isopropylheptamethylene; and diacid-derived structural units of the formula

Description

10'7~'7~0 25334 POLY~MIDES
This invention relates to polyamides. In a specific aspect the in-vention relates to polyamides formed from branched C10 diamdnes and straight chain aliphatic dicarboxylic acids having 6, 8, 10 and/or 12 carbon atoms.
The use of commercially available polyamides in the formulation of adhesives, for example, hot melt structural adhesives, has gained in accep-tance. However, in some applications such as the sterilization of metal cans in boiling water or with steam, it is desirable that the adhesive have a great-; er boiling water resistance than is provided by some of the commercially avail-able polyamides.
Accordingly, it is an object of the invention to provide a new poly-amide which has good boiling water resistance. It is an object of the inven-tion to provide a polyamide which has a good lap shear strength even after exposure to boiling water. It is also an object of the invention to provide a polyamide which has a good peel strength as well as good lap shear strength.
Another object of the invention is to provide an improved polyamide adhesive.
Other objects, aspects, and advantages of the invention will be apparent from a study of the specification and the appended claims to the invention.
In accordance with the present invention it has been found that the foregoing objectives can be achieved by producing a polyamide having diamine-derived primary structural units of the formula H H
- N - A - N -wherein each A is individually selected from the group consisting of 5-methyl-nonamethylene, 2,4-dimethyloctamethylene, 2,4,6-trimethylheptamethylene, and 4-isopropylheptamethylene; and diacid-derived primary structural units of the formula O O
- ~ - (CH2)n - ~ -wherein each n is an integer individually selected from the group consisting of 4, 6, 8, and 10.

107~;740 The A in each of the diamine-derived primary structural units can be solely 5-methylnonamethylene, 2,4-dimethyloctamethylene, 2,4,6-trimethylhepta-methylene, or 4-isopropylheptamethylene, but preferably the polyamlde contains a mixt~re of diamine-derived primary structural units wherein A in some of the units is S-methylnonamethylene and the A in other units is 2,4-dimethylocta-methylene, with at least 20 percent, preferably at least 50 percent, more pref-erably at least 70 percent, and even more preferably at least 80 percent, by number, of the A's being 5-methylnonamethylene. Other isomeric diamine-derived primary structural units can be also present wherein the A in some of the units is 2,4,6-trimethylheptamethylene and/or the A in some of the units is 4-iso-propylheptamethylene. In an exemplary embodiment, 20 to 96 percent, by number, of the A's are 5-methylnonamethylene, 4 to 80 percent, by number, of the A's are 2,4-dimethyloctamethylene, 0 to 25 percent, by number, of the A's are 2,4,6-trimethylheptamethylene, and O to 25 percent, by number, of the A's are 4-isopropylheptamethylene. In a presently preferred embodiment 70 to 96 percent, ;
by number, of the A's are S-methylnonamethylene, 4 to 30 percent, by number, of , the A's are 2,4-dimethyloctamethylene, 0 to lS percent, by number, of the A's ' are 2,4,6-trimethylheptamethylene, and O to lS percent, by number, of the A's -~ -' are 4-isopropylheptamethylene. ~
The diamine-derived primary structural units can be obtained from -principal diamines having the formula H2N-A-NH2 wherein each A is individually selected from the group consisting of S-methylnonamethylene, 2,4-dimethylocta-methylene, 2,4,6-trimethylheptamethylene, and 4-isopropylheptamethylene. The principal diamine can consist essentially of any one of S-methyl-l,9-nonane-diamine, 2,4-dimethyl-1,8-octanediamine, 2,4,6-trimethyl-1,7-heptanediamine, or 4-isopropyl-1,7-heptanediamine, or mixtures of any two or more thereof, but preferably comprises-a mixture of 5-methyl-1,9-nonanediamine and 2,4-dimethyl-1,8-octanediamine, with the S-methyl-1,9-nonanediamine constituting at least 20, preferably at least SO, more preferably at least 70, and even more prefer-ably at least 80, mole percent of the mixture. 2,4,6-Trimethyl-1,7-heptane-diamine and/ar 4-isopropyl-1,7-heptanediamine can be present in the mixture.

.

11~7~7~0 An exemplary suitable mixture for use as the principal diamine comprises 20 to 96 mole percent 5-methyl-1,9-nonanediamine, 4 to 80 mole percent 2,4-di-methyl-1,8-octanediamine, 0 to ~5 mole percent 2,4,6-trimethyl-1,7-heptanedi-amine, and O to 25 mole percent 4-isopropyl-1,7-heptanediamlne. A presently preferred mlxture for use as the principal diamine comprises 70 to 96 mole per-cent 5-methyl-1,9-nonanediamine, 4 to 30 mole percent 2,4-dimethyl-1,8-octane-diamine, O to 15 mole percent 2,4,6-trimethyl-1,7-heptanediamine, and O to 15 mole percent 4-isopropyl-1,7-heptanediamine.
The diacid-derived primary structural units can be obtained from the principal diacid components having the formula ~, O O
Q - C - (CH2)n - C - Q

wherein each Q is individually selected from the group consisting of -OH, bra-mine, chlorine, alkoxy radicals having 1 to 4 carbon atoms, and phenoxy, and each n is an integer individually selected from the group consisting of 4, 6, 8, and 10. Preferably, each Q is -OH. Exemplary principal diacid components include adipic acid, suberic acid, sebacic acid, dodecanedioic acid, adipoyl chloride, adipoyl bromide, suberoyl chloride, suberoyl bromide, sebacoyl chloride, sebacoyl bromide, dodecanedioyl bromide, dodecanedioyl chloride, dimethyl adipate, dibutyl adipate, methyl ethyl adipate, dimethyl suberate, dimethyl sebacate, dimethyl dodecanedioate, diisopropyl suberate, dibutyl do-decanedioate, diphenyl dodecanedioate, and the like, and mixtures of any two or more thereof.
If desired, the polyamide can contain secondary structural units derived from other diamines, diacids, amino acids and/or lactams. In such a polyamide the nitrogen atoms provided by the diamine-derived primary structural . .
. units constitute at least 70 percent, preferably at least 80 percent, more preferably at least 90 percent, and even more preferably at least 95 percent, by number, of the total nitrogen atoms in the polyamide. Similarly, the car-bonyl groups provided by the diacid-derived primary structural units constitute at least 70 percent, preferably at least 80 percent, more preferably at least .

10767~0 90 percent, and even more preferably at least 95 percent, by number, of the total carbonyl groups in the polyamide.
The secondary structural units can have the formula ~ ~
R R 0 0 R 0 ~ ;
- N - G - N - , - C - Z - C - , or - N - J - C -wherein each R is individually selected from the group consisting of hydrogen and alkyl radicals having from 1 to 6 carbon atoms per radical, each G i8 individually selected from the group consisting of divalent acyclic hydrocar-bon radicals having from 6 to 16 carbon atoms, each Z iB individually selected ; 10 from the group consisting of divalent hydrocarbon radicals having from 5 to 12 carbon atoms, and each J is individually selected from the group consisting of divalent acyclic hydrocarbon radicals having from 5 to 13 carbon atoms. These secondary structural units can be obtained from one or more other diamines having the formula RHN-G-NHR, one or more other diacid components having the formula O O ', :' Q - C - Z - C - Q, one or more amino acids having the formula .
RHN - J - C02H, and/or one or more lactams having the formula R - N - J , wherein R, G, Q, Z, and J are as hereinbefore defined, . 20 C = 0 ~ each Q preferably belng -OH.
Thus, there can be employed in the preparation of the polyamide a minor amount of a diamine such as hexamethylenediamine, octamethylenediamine, nonamethylene- ~ ~;
diamine, decamethylenediamine, hexadecamethylenediamine, N-methylhexamethylene-diamine, N,N'-dimethylhexamethylenediamine, N,N~-diethyloctamethylenediamine, N-isopropyl-N'-butyldecamethylenediamine, N,N'-dihexylhexadecamethylenediamine, and/or a minor amount of a dicarboxylic acid or derivative thereof such as ~ pimelic acid, azelaic acid, undecanedioic acid, tridecanedioic acid, tetra-i! decanedioic acid, 1,4-cyclohexanedicarboxYliC acid, terePhthalic acid, pimeloyl 30 chloride, azelaoyl bromide, diphenyl azelate, dimethyl pimelate, diethyl azela '' , . ~ .

10767~0 undecanedioyl chloride, diisopropyl azelate, dibutyl tetradecanedioate, or di-methyl terephthalate; and/or a minor amount of an amino acid such as 6-amino-hexanoic acid, 8-aminooctanoic acid, 10-aminodecanoic acid, 12-aminododecanoic acid, N-methyl-6-amdnohexanoic acid, N-ethyl-7-aminoheptanoic acid, N-isopropyl-12-aminododecanoic acid, or N-hexyl-14-aminotetradecanoic acid; and/or a minor amount of a lactam such as the lactam of any of the above-named amino acids.
When present, the secondary structural units will generally provide from 0.01 to 30 percent, preferably from 1 to 25 percent, by number, of the nitrogen atoms and/or from 0.01 to 30 percent, preferably from 1 to 25 percent, by num-ber, of the carbonyl groups in the polyamide.
The diamine(s) and the diacid component(s) can be individually intro-duced into the polycondensation reaction zone and therein be subjected to suit-able polycondensation reaction conditions. Alternatively, at least a portion of the diamine(s) can be r~acted with at least a portion of the dicarboxylic acid(s) to form the corresponding salt(s). The preformed salt(s), together with any additional amounts of diamine(s) and/or dicarboxylic acid(s), can be introduced into the polycondensation reactor and therein be subjected to suit-able polycondensation reaction conditions. In the polycondensation reaction zone, the molar ratio of the total diamine(s) to the total diacid component(s) will generally be substantially l:l, although a slight excess, e.g., up to 5 mole percent, of the diamine(s) or the diacid component(s) can be used.
The polyamides of this invention can be prepared ùnder any suitable polycondensation conditions. In general, in a preferred procedure in which the diacid components are employed as dicarboxylic acids, the mixture of monomers and/or salts thereof can be heated at temperatures in the range of about 200 toabout 340C, preferably in the range of about 260 to about 320C, for a period of time in the range of about 1 hour to about 24 hours, preferably in the range of about 1.5 hours to about 8 hours. The pressure normally reaches a maximum of not more than about 1,000 psig, preferably not more than about 600 psig, and is allowed to diminish by venting gaseous material, sometimes with the aid of an inert gas, the final heating being conducted at a pressure as low as about 1 mm .

- - , .
.

1(~76740 Hg, preferably in the range of about 10 to about 50 mm Hg. If desired, the mixtures of monomers and/or salts can be heated at a lower temperature, e.g., in the range of about 200 to about 230C, for a period of time, e.g., in the range of about l/2 hour to about 16 hours, prior to the heating to a tempera-ture in the range of about 260 to about 320C. Water can be present to serve as a heat transfer agent and to aid in keeping the reactants in the reaction zone. Acetic acid can be present, if desired, in an amount up to about 2 mole percent based on the total diacid, to control and stabilize the molecular ~ -weight of the polyamide. A thermoxidative stabilizer such as manganese lactate can be employed, if desired.
When diacid components other than dicarboxylic acids are employed, -~
reaction conditions known in the art for use with such diacid components, some-times differing from those described above, can be used in the production of the polyamides of this invention.
The polyamides of this invention can be employed as molding resins, as hot melt adhesives, or in the production of coatings or films. In general the polyamides of this invention will have an inherent viscosity (as measured at 30C in a m-cresol solution having a polymer concentration of 0.5 gram/100 milliliters solution) of at least 0.4, preferably in the range of 0.6 to 2.
In general, when used as hot melt adhesives, the polyamides of this invention will have a "T"-peel strength (determined as shown in Table I and footnotes thereto) for aluminum-to-aluminum bonding of at least 3 pounds per inch width, preferably of at least 4 pounds per inch width, and more preferably of at least 5 pounds per inch width; a lap shear etrength (ASTM D 1002-72) for aluminum-- to-aluminum bonding of at least 1000, preferably at least 1200, and more pref-erably at least 1500 pounds per square inch of shear area; and a percentage retention of lap shear strength at 25C after exposure to boiling water for 24 hours of at least 50 percent, preferably at least 60 percent, and more pref-erably at least 70 percent.
The polyamides of this invention can be blended with various addi-tives such as fillers, pigments, stabilizers, softeners, extenders, or other :

polymers. For example, there can be incorporated in the polymers of this in-vention substances such as graphite, carbon black, titanium tioxide, glass fibers, carbon fibers, metal powders, magnesia, silica, asbestos, wollastonite, clays, wood flour, cotton floc, alpha cellulose, mica, and the like. If desired, such additives can be added to the polymerization reactor.
The following data are presented in further illustration of the in-vention, but should not be construed in undue limitation thereof.
EXAMPLE I
In each of a series of runs a mixture of the isomeric diamine, the diacid, and distilled water were charged to a stirred autoclave. The autoclave was alternately pressured with nitrogen and evacuated several times, then sealed under a pressure of 40-60 psig nitrogen. The autoclave was then heated from about 25C to 210C during about 1/2 hour, maintained substantially at 210C for 1 - 2-1/2 hours, heated from 2109 to a temperature within the range of 280 to 300C during a period of 1/2 to 1 hour, and heated substantially at 280 to 300C for 1/2 to 1 hour, all the while venting as necessary to maintain the pressure at 400 to 500 psig, after this pressure was attained. Unless otherwise indicated, the autoclave was then heated substantially at 280 to 300C, first for 1/2 hour while venting to 0 psig, then for 1/2 hour under a ` 20 flow of nitrogen at substantially atmospheric pressure, then for 1/4 to 1/2 ` hour while reducing the pressure to about 20 to about 25 mm Hg, and finally for 1/2 to 1 hour at about 20 to about 25 mm Hg. The resulting polyamide was re-moved from the autoclave, and properties thereof were determined. These prop-erties are shown in Table I. Flexural modulus, tensile strength, and elongation were determined on samples compression molded at 218C, except in runs 2 and 5, as noted in Table I. Also shown in Table I are properties of Milvex 1235 poly-amide, listed therein as "control".

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In run 2 the charge was 2314.64g (13.433 moles) of a mixture of ~ -isomeric diamines consisting of 89.8 mole percent 5-methyl-1,9-nonanediamine, 9.8 mole percent 2,4-dimethyl-1,8-octanediamine, 0.1 mole percent 2,4,6-tri-methyl-1,7-heptanediamine, and 0.3 mole percent 4-isopropyl-1,7-heptanediamine;
1943.66 g (13.3 moles) of adipic acid; 0.1984 g manganese lactate; and 1064.58 g water.
In run 3 the charge was 86.16 g (0.5 mole) of a mixture of isomeric diamines consisting of 89.6 mole percent 5-methyl-1,9-nonanediamine, 10.0 mole percent 2,4-dimethyl-1,8-octanediamine, 0.1 mole percent 2,4,6-trimethyl-1,7-heptanediamine, and 0.3 le percent 4-isopropyl-1,7-heptanediamine, 80.09 g - (0.5 mole) pimelic acid; 0.005 g manganese lactate; and 42 g water.
In run 4 the charge was 86.16 g (0.5 mole) of the same mixture of isomeric diamines shown for run 3; 87.09 g (0.5 mole) suberic acid; 0.005 g l manganese lactate; and 44 g water.
'~J In run 5 the charge was 1202.72 g (6.98 moles) of the same mixture i of isomeric diamines shown for run 2; 1313.77 g (6.98 moles)azelaic acid;
0.1189 g manganese lactate; and 629.12 g water. The final pressure used in the polymerization was about 75 mm Ng.
In run 6 the charge was 86.16 g (0.5 mole) of the same mixture of isomeric diamines shown for run 3; 101.13 g (0.5 mole) sebacic acid; 0.005 g manganese lactate; and 46.8 g water.
In run 7 the charge was 86.16 g (0.5 mole) of the æame mixture of isomeric diamines shown ~f~r run 3; 115.15 g (0.5 mole) dodecanedioic acid;
0.005 g manganese lactate; and 50.32 g water.
A comparison of the polyamides of the present invention (runs 2, 4, 6, and 7) with the com~ercial hot melt adhesive (run 1) demons~rates that the polyamides of the present invention have substantially better "T"-peel strength values than the control as well as retaining substantially greater percentage of their lap shear strength after 24 hours exposure to boiling ~ 7~ra~/em~9~f~ -10-~' ' ' : '' la767~0 water than the control. A comparison of the polyamides of runs 2, 4, 6, and 7 with the polyamides employing diacid with an odd number of carbon atoms (runs 3 and 5) demonstrateg that the polyamides of the pre9ent invention are much more resistant to hot water, as indicated by the values or percentage retention of lap shear strength, than the polyamides of diacids having an odd number of carbon atoms. The values for tensile strength, elongation, and flex-ural modulus shown for the polyamides of the present invention illustrate the utility of these polyamides as molding resins.
Reasonable variations and modifications are possible within the scope of ehe foregoing dlsclosoFe and the appended clal=s to the in~erltion.

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Claims (18)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A normally solid, moldable polyamide comprising:
diamine-derived primary structural units of the formula wherein each A is individually selected from the group consisting of 5-methyl-nonamethylene, 2,4-dimethyloctamethylene, 2,4,6-trimethylheptamethylene, and 4-isopropylheptamethylene; and diacid-derived primary structural units of the formula wherein each n is an integer and is 4, 6, 8, or 10;
the nitrogen atoms provided by said diamine-derived primary struct-ural units constituting at least 70 percent, by number, of the total nitrogen atoms in said polyamide; the carbonyl groups provided by said diacid-derived structural units constituting at least 70 percent, by number, of the total carbonyl groups in said polyamide; the balance, if any, of the nitrogen atoms and carbonyl groups in said polyamide being provided by secondary structural units selected from the group consisting of , , and wherein each R is individually selected from the group consisting of hydrogen and alkyl radicals having from 1 to 6 carbon atoms per radical, each G is a divalent acyclic hydrocarbon radical having 6 to 16 carbon atoms, each Z is a divalent hydrocarbon radical having from 5 to 12 carbon atoms and each J is a divalent acyclic hydrocarbon radical having from 5 to 13 carbon atoms.

2. A polyamide in accordance with claim 1 wherein at least 80 per-cent, by number, of the nitrogen atoms in said polyamide are provided by said diacid-derived primary structural units.

3. A polyamide in accordance with claim 2 wherein at least 90 per-cent, by number, of the nitrogen atoms in said polyamide are provided by said diamine-derived primary structural units, and at least 90 percent, by number, of the carbonyl groups in said polyamide are provided by said diacid-derived primary structural units.

4. A polyamide in accordance with claim 3 wherein said polyamide is a linear polymer consisting essentially of said diamine-derived primary structural units and said diacid-derived primary structural units.

5. A polyamide in accordance with claim 4 wherein the A in at least 50 percent, by number, of said diamine-derived primary structural units is 5-methylnonamethylene and the A in each of the balance, if any, of said diamine-derived primary structural units is individually selected from the group con-sisting of 2,4-dimethyloctamethylene, 2,4,6-trimethylheptamethylene, and 4-isopropylheptamethylene.

6. A polyamide in accordance with claim 3, 4 or 5 wherein each n is 4.

7. A polyamide in accordance with claim 3, 4 or 5 wherein each n is 6.

8. A polyamide in accordance with claim 3, 4 or 5 wherein each n is 8.

9. A polyamide in accordance with claim 3, 4 or 5 wherein each n is 10.

10. A polyamide in accordance with claim 1 wherein the A in at least 50 percent, by number, of said diamine-derived primary structural units is 5-methylnonamethylene and the A in each of the balance, if any, of said diamine-derived primary structural units is individually selected from the group con-sisting of 2,4-dimethyloctamethylene, 2,4,6-trimethylheptamethylene, and 4-isopropylheptamethylene.

11. A polyamide in accordance with claim 1 wherein the A in at least 70 percent, by number, of said diamine-derived primary structural units is 5-methylnonamethylene and the A in each of the balance, if any, of said diamine-derived primary structural units is individually selected from the group con-sisting of 2,4-dimethyloctamethylene, 2,4,6-trimethylheptamethylene, and 4-isopropylheptamethylene.

12. A polyamide in accordance with claim 1, 10 or 11 wherein each n is 4.

13. A polyamide in accordance with claim 1, 10 or 11 wherein each n is 6.

14. A polyamide in accordance with claim 1, 10 or 11 wherein each n is 8.

15. A polyamide in accordance with claim 1, 10 or 11 wherein each n is 10.

16. A polyamide in accordance with claim 1, 10 or 11 having a per-centage retention of lap shear strength at 25°C, as determined by the method of ASTM D 1002-72 after exposure to boiling water for 24 hours of at least 50 percent for aluminum-to-aluminum bonding with said polyamide.

17. A polyamide in accordance with claim 1, 10 or 11 having a per-centage retention of lap shear strength at 25°C, as determined by the method of ASTM D 1002-72 after exposure to boiling water for 24 hours of at least 50 percent for aluminum-to-aluminum bonding with said polyamide and having a lap shear strength at 25°C, as determined by the method of ASTM D 1002-72 of at least 1000 pounds per square inch.

18. A polyamide in accordance with claim 1, 10 or 11 having a per-centage retention of lap shear strength at 25°C, as determined by the method of ASTM D 1002-72 after exposure to boiling water for 24 hours of at least 50 percent for aluminum-to-aluminum bonding with said polyamide, a lap shear strength value, as determined by the method of ASTM D 1002-72 for aluminum-to-aluminum bonding, of at least 1200 pounds per square inch, and a "T"-peel strength of at least 5 pounds per inch width.