Claims
- 1. A polyamide copolymer comprising diamine monomer
- repeat units of the formula ##STR12## where n is 10 or 12 and repeat units of the formula ##STR13## derived from a symmetrical diacid or derivative of said diacid and where Ar is an aromatic group, and a sufficient amount of units of at least one additional comonomer selected from the group consisting of:
- 4. 11-dioxa-tetradecane-1,14-diamine,
- 4,9-dioxa-1,12-diaminododecane,
- lactams having up to 9 methylene groups in the lactam ring,
- telechelic amine terminated polyolefins,
- bis(aminoalkyl)polytetramethylene oxide, and,
- bis(aminoalkyl)poly(dimethylsiloxane),
- whereby the copolymer exhibits, a water absorption according to ASTM D 570-81 of less than or equal to 5 percent by weight of the copolymer, and the copolymer has a crystalline melting point in the range of 250-300 deg.C.
- 2. The copolymer according to claim 1 wherein the symmetrical diacid or derivative thereof is at least one selected from the group consisting of: terephthalic acid, 2,6-naphthalene dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid, and dimethyl terephthalate.
- 3. The copolymer according to claim 2 wherein the symmetrical diacid or derivative thereof is terephthalic acid.
- 4. The copolymer according to claim 1 wherein the diamine monomer repeat units are derived from 1,12-dodecanediamine.
- 5. The copolymer according to claim 1 wherein the comonomer has block copolymer units which block comonomer units having a molecular weight in the range of 200-6000.
- 6. A polyamide copolymer comprising units derived from dodecanediamine, and terephthalic acid or a derivative of terephthalic acid, and a sufficient amount of at least one additional comonomer selected from the group consisting of:
- 4,11-dioxa-tetradecane-1,14-diamine,
- 4,9-dioxa-1,12-diaminododecane,
- lactams having up to 9 methylene groups in the lactam ring,
- telechelic amine terminated polyolefins,
- bis(aminoalkyl)polytetramethylene oxide, and,
- bis(aminoalkyl)poly(dimethylsiloxane)
- whereby the copolymer exhibits a water absorption according to ASTM D 570-81 of less than or equal to 5 percent by weight of the copolymer, and the copolymer has a crystalline melting point in the range of 250-300 deg.C.
- 7. The copolymer according to claim 6 wherein the additional comonomer comprises up to 30 percent by weight of the copolymer.
- 8. The copolymer according to claim 6 which exhibits crystallization of at least 20 percent measured according to x-ray diffraction.
- 9. The copolymer according to claim 6 which exhibits a crystalline melting point in the range of 270-290 deg.C.
- 10. The copolymer according to claim 6 wherein the telechelic amine terminated polyolefins are at least one selected from the group consisting of: polyethylene, poly(ethylenepropylene), and polyisobutylene.
- 11. The copolymer according to claim 6 wherein the telechelic amine terminated polyolefins are at least one selected from the group consisting of: polyethylene, poly(ethylenepropylene), and polyisobutylene.
SUMMARY OF THE INVENTION
This application is a continuation of application Ser. No. 388,182 filed July 31, 1990 now abandoned.
BACKGROUND OF THE INVENTION
The present invention is in the field of polyamides, more particularly, the present invention relates to copolymers derived from long chain diamines, a symmetrical diacid or derivative thereof, and at least one specifically selected additional comonomer.
Conventional aliphatic nylons such as polycaprolactam (nylon 6), poly(hexamethylene adipamide) (nylon 6,6) have high melting points and are thermoplastically processable. However, they have undesirably high water absorption characteristics, absorbing from 8 to 12 wt. percent water. Water absorption causes dimensional growth, and plasticization with a significant reduction in stiffness. This makes them unsuitable for various end use applications.
Long chain aliphatic polyamides such as polylaurolactam (nylon 12), and poly(1,12-dodecamethylene dodecanamide) (nylon 12,12) have low moisture-absorbing properties, but have undesirably low melting points (below 180.degree. C.). Symmetrical rigid, aromatic diacids, such as terephthalic acid monomers used with aliphatic diamines having from 6 to 12 carbon atoms result in polyamides having low moisture absorbing characteristics but undesirably high melting points (greater than 300.degree. C.). Such melting points are often above the nylon degradation temperatures so that the polyamide cannot be melt-polymerized or melt-processed.
The present invention is an improved polyamide copolymer derived from a long chain diamine, preferably RHN[CH.sub.2 ].sub.n NHR, where n is from 10 to 14, and preferably is 12 (i.e., 1,12-dodecanediamine) and R is preferably H or an alkyl carbonyl group such as ##STR2## resulting in the monomer repeat unit ##STR3## and a symmetrical diacid or derivative thereof, preferably ##STR4## where Ar is an aromatic group, and R' is preferably --OH, alkoxy group such as --OCH.sub.3, or a halogen, resulting in the monomer repeat unit ##STR5## Preferably the diacid is a symmetrical aromatic dicarboxylic acid. The symmetrical aromatic diacid or derivative thereof is preferably selected from the group consisting of terephthalic acid, 2,6-naphthalene dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid and dimethyl terephthalate. The copolymer has minor amounts, preferably 3 to 30 and more preferably 5 to 10 mol percent, of an additional comonomer.
Useful and preferred additional comonomers include units derived from monomers which are difunctional. The functional groups are groups which are reactive with the amine groups of the diamine or the acid groups of the diacid. Preferred functional groups include amine groups, hydroxyl groups and carboxylic acid groups. Specific and preferred comonomers include lactams having up to 9 methylene groups, nonsymmetrical aromatic diacids, and hydroxy terminated polyolefins or polyethers. Depending upon the comonomer, the resulting polyamide copolymer will have high crystallinity and low moisture absorption, or the additional comonomer will contribute a "soft segment" making the polyamide copolymer more flexible.
Additional comonomers which result in the improved crystallinity and low moisture absorption of the polyamide copolymer are preferably present in an amount sufficient to reduce the melting point while at the same time enable the polymer to have high crystallinity and low moisture absorption properties. Preferably, the additional comonomer results in a polyamide copolymer having relatively high crystalline melting points of preferably from 250.degree. C. to 300.degree. C., and more preferably 270.degree. C. to 290.degree. C., high crystallinity, preferably at least 20 percent, and low moisture absorption, preferably below 5 percent, and more preferably below 3 weight percent based on the weight of polyamide copolymer and moisture. The additional comonomer can be preferably present in random or block segments thereby resulting in a random or block copolymer. The major blocks of polyamide are derived from the long chain diamine and the symmetrical diacid. Preferred additional comonomers include diamines and nonsymmetrical diacids. Preferred diamines include 4,9-dioxa-dodecane-1,12-diamine; 4,11-dioxa-tetradecane-1,14-diamine; caprolactam, and laurolactam. Preferred nonsymmetrical diacids include phthalic acid and isophthalic acid.
Comonomers which result in a polyamide copolymer having a flexible (low glass transition temperature, Tg), hydrophobic structure include block segments of polyolefin polyether and polysiloxane and the like. Preferred segments include telechelic amine terminated polyolefins including polyethylene, poly(ethylene-propylene), polyisobutylene, poly(ethylene-butene), and the like. Preferred polyether, is bisamino alkyl, polytetramethyleneoxide (derived from polytetrahydrafuran), and preferred polysiloxane is poly(dimethyl siloxane); i.e., alpha,-omega-bisaminoalkyl poly(dimethyl siloxane). These comonomers have been found to act as a "soft segment" when used in the form of a block copolymer. The resulting copolymer has a combination of properties including high ductility (tensile-elongation), heat and chemical resistance, and low moisture absorption properties. They are useful for extrusion and molding applications.
The present invention is a polyamide copolymer comprising units derived from a long chain diamine preferably RHN[CH.sub.2 ].sub.n NHR, where n is from 10 to 14 and preferably is 12 (i.e., 1,12-dodecanediamine); and R is preferably H or an alkyl carbonyl group such as ##STR6## resulting in the monomer repeat unit ##STR7## a symmetrical diacid and derivatives thereof, preferably a symmetrical aromatic diacid and derivatives thereof, preferably ##STR8## where Ar is an aromatic group, and R' is preferably --OH, alkoxy group such as --OCH.sub.3, or a halogen resulting in the monomer repeat unit ##STR9## and an additional comonomer. Useful Ar's include ##STR10## and the like. The aromatic groups can contain substituents which do not adversely affect the properties of the polyamide copolymer. The symmetrical aromatic diacid is preferably selected from the group consisting of terephthalic acid, 2,6-naphthalene dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid and dimethyl terephthalate. The preferred polyamide copolymer has units derived from 1,12-dodecanediamine copolymerized with a terephthalic acid and the additional comonomer. The copolymer comprises from 35 to 48.5 mol, and preferably 40 to 45 mol percent of units derived from the long chain diamine preferably dodecanediamine, from 35 to 48.5, and preferably from 40 to 45 mol percent of units derived from terephthalic acid or derivatives thereof. Additionally, the copolymer comprises at least 3, and preferably from 3 to 30, and more preferably from 5 to 10 mol percent of units derived from the additional comonomer.
A preferred embodiment has units derived from at least one additional comonomer which results in a copolymer having a relatively high melting point, high crystallinity, and has low moisture absorption characteristics. The preferred polyamide copolymer has a melting point below a copolymer derived from a corresponding long chain diamine and symmetrical diacid or derivative thereof (i.e., dodecanediamine and terephthalic acid) of the same molecular weight. The melting point of the preferred polyamide copolymer is preferably in the range of from 250.degree. C. to 300.degree. C., and more preferably 270.degree. C. to 290.degree. C. The polyamide copolymer is highly crystalline as measured by X-ray diffraction. The polyamide copolymer is preferably at least 20 percent, and more preferably at least 30 percent. The upper range of crystallinity is typically 40 percent mol and preferably 50 percent crystalline. Additionally, the polyamide copolymer has low moisture absorption characteristics as measured according to ASTM D 570-81. Preferably the polyamide copolymer absorbs less than 5 percent by weight, and preferably less than 3 percent by weight of moisture based on the weight of the polyamide copolymer and moisture.
Preferred additional comonomers which lead to cocrystallizable segments, or at least do not significantly reduce crystallinity are diamines such as 4,9-dioxa-1,12-diaminododecane; 4, 11-dioxa-tetradecane-1,14-diamine; non-symmetrical diacids including isophthalic acid; lactams having up to 8 methylene groups, preferably laurolactam and caprolactam. Copolyamides made using these additional comonomers have been found to have crystalline melting points of from 270.degree.-285.degree. C., a low water absorption character of 1.7-3 percent by weight when measured according to ASTM D 570-81, good melt processability, at or below 300.degree. C., and satisfactory mechanical properties including strength and toughness. The copolyamides have been found to have excellent chemical resistance, particularly to aqueous zinc chloride solutions.
Additionally, the polyamide copolymers have been found to be dimensionally stable when exposed to heat and moisture, and have chemical resistance to gasoline and alcohol as well as a variety of other organic materials. This makes the copolymers of the present invention useful for a variety of high-performance engineering resin applications, such as automotive under-the-hood parts, fuel lines, and fuel component parts.
An alternate embodiment of the polyamide copolymer can include comonomer units to improve flexibility of the copolymer. Comonomers having a flexible hydrophobic structure resulting in a soft segment include the olefins present as polyolefin segments such as polyethylene, poly(ethylene-propylene), polyisobutylene, poly(ethylenebutene), and the like. A preferred ether is a polyether such as bis[aminopropyl]polytetrahydrafuran (derived from polytetramethyleneoxide); alpha,omega-bis(aminoalkyl)poly(tetramethyleneoxide); alpha,omega-diamino polyolefins; i.e., telechelic, amino terminated polyethylene; and polysiloxanes such as poly(dimethyl siloxane); i.e., alpha,omega-bisaminoalkyl poly(dimethyl siloxane). The molecular weight of the soft segments preferably range from 200 to 6,000 and more preferably from 750 to 2100. Polyethylene oxide is not preferred because of the high water absorption.
The additional comonomer preferably is derived from comonomers resulting in units having the formula ##STR11## wherein
R.sup.2 is selected from --H, --CH.sub.3, --C.sub.2 H.sub.5, --Cl, --CH.dbd.CH.sub.2, and mixtures thereof,
R.sup.3 is selected from --H, --CH.sub.3, --C.sub.2 H.sub.5, --CH--CH.sub.2, and mixtures thereof,
A is selected from H, a halogen, and a hydrocarbon having from 1 to 4 carbon atoms,
p is from 5 to 80,
q is from 10 to 80,
r is from 1 to 30, preferably 5 to 30,
s is from 4 to 9,
x is from 4 to 6, and
x' is from 2 to 6.
The copolymer of the present invention can be made by conventional methods to copolymerize polyamides. Particularly preferred are melt polymerization techniques in which the monomers are melted together under an inert atmosphere. The melt polymerization preferably is conducted at from 275.degree.-320.degree. C., and more preferably from 295.degree.-320.degree. C.
In addition to the three principle monomeric constituents, which together produce the copolymer of this invention, other polymerizable monomers can also be used to prepare copolymers. Included in these are vinyl compounds and other monomers which could be polymerized directly into a linear polymer chain. The quantity of such additional monomers can vary and can be up to 30 mol percent of the total number of polymerizable constituents but preferably is limited to quantities of less than 15 mol percent, more preferably less than 5 mol percent.
US Referenced Citations (13)
Non-Patent Literature Citations (3)
| Entry |
| Chemical Abstract, vol. 78, No. 8, 2/26/73, p. 64, Abstract 44934X, Tsuda. |
| Journal of Polymer Science, vol. VIII, No. 1, pp. 1-19, "The p-Phenylene Linkage in Linear High Polymers; Some Structure-Property Relationships" Owen B. Edgar, Rowland Hill, 1958. |
| Saotome et al., Polyamides Having Long Methylene Chain Units, J. Pol. Sci. Part A-1, vol. 4, pp. 1463-1473 (1966). |
Continuations (1)
|
Number |
Date |
Country |
| Parent |
388182 |
Jul 1989 |
|
Patent Grant
5079339
