Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
1999-12-22
2001-08-14
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S323000, C528S324000, C528S332000, C528S335000, C528S345000, C525S420000, C525S432000
Reexamination Certificate
active
06274697
ABSTRACT:
FIELD OF THE INVENTION
Disclosed in the present invention is a process for modifying a polyamide polymer comprising contacting an epoxy containing molecule with diamine/diacid salt and/or an amino-acid of a hydrolyzed lactam or lactam to form a modified polyamide. A second embodiment of the present invention is a process for modifying a polyamide polymer comprising contacting an epoxy containing molecule with diamine then contacting the resulting modified diamine with diacid and/or lactam to form a modified polyamide.
Many of the products produced have higher viscosity, more end groups, improved characteristics such as enhanced dyeing and higher moisture absorption, and enhanced adhesion to other substrates.
TECHNICAL BACKGROUND
U.S. Pat. No. 5,175,038 relates to a highly bulked continuous filament yarns, comprised of filaments having a denier per filament of 10-25 and a trilobal filament cross section of modification ratio 1.4-4.0, including filament nylon yarns that have a yarn bulk level of at least 35, which can be ply-twisted together to high-twist levels and can be used in carpets at high-twist levels.
U.S. Pat. No. 3,962,159 discloses graft copolymers prepared by condensing a polyamideamine substrate with starch and a condensing reagent.
SUMMARY OF THE INVENTION
Disclosed in the present invention is a process for modifying a polyamide polymer comprising contacting an epoxy containing molecule with diamine/diacid salt and/or an amino-acid of a hydrolyzed lactam or lactam to form a modified polyamide.
A second embodiment of the invention is a process for modifying a polyamide polymer comprising contacting an epoxy containing molecule with diamine then contacting the resulting modified diamine with diacid and/or lactam to form a modified polyamide.
An example of a lactam that may be hydrolyzed in the present invention is caprolactam, commonly used in the manufacture of nylon 6.
Also disclosed is a polyamide having a substituted or unsubstituted 2-hydroxy-ethyl modifier group pendant from the amide nitrogen.
DESCRIPTION OF THE INVENTION
The production of aliphatic and aromatic polyamides, particularly nylons including nylon 6, nylon 6,6 and their copolymers, is well known. These polymers contain amide, acid and amine groups, which can be substituted with moieties which can modify the properties, such as dyeability, tensile strength, catalytic activity, and the like. See generally U.S. Pat. Nos. 5,422,420, 5,223,196, 3,389,549, which are incorporated herein by reference. See also Kirk Othmer Encyclopedia of Chemical Technology, 4th ed., 1996, Vol. 19, pp. 454-518, and Ullmann's Encyclopedia of Industrial Chemistry, 1992, Vol. A21, pp. 190-191.
The present invention allows the production of modified aliphatic and aromatic polyamides and other amide-, amine- or carboxylic acid-containing polymers and copolymers, particularly nylons and aramids, including but not limited to nylon 6, nylon 6,6, Kevlar® and Nomex®, in a new way that is not currently available. For example, the pendant substituted or unsubstituted 2-hydroxy-ethyl can act as a branch site on the nylon chain by reacting with a terminal acid group in a another polymer chain to form an ester branch linkage. This produces higher viscosity in shorter reaction time and accelerates autoclave polymerization, continuous polymerization and solid phase polymerization, which are practiced with polyamides. In general, the present improvement can be used with any process useful for making polyamides and other polymers, as described in the background above, including batch and continuous polymerization processes. No equipment modification is generally necessary, as additional ports on evaporators, transfer lines and autoclaves are generally available for addition of process and product property control additives. Additives include, but are not limited to, antifoam agents, antioxidants, delusterants, antistatic agents, branching agents and the like.
The modifying process of the present invention comprises, contacting a primary terminal amine group on a monomer or polymer/oligomer molecule with an epoxy containing molecule producing a produce referred to herein as “modified amine”, then contacting the modified amine with diacid or a terminal acid group in a polymer/oligomer chain, additional diamine, diacid and/or lactams, to form a polyamide polymer with 2-hydroxy-ethyl (substituted or unsubstituted) groups pendant on a portion of the amide nitrogens, or a substituted terminal group on the polymer chain.
Typically, in a nylon 6,6 process, hexamethylenediammonium adipate salt (approximately 52% by weight in water) is added to an evaporator. Various additives may be added at this stage. Under inert atmosphere, this reaction mixture is then heated to a boil (about 160° C.) under slight pressure to remove the excess water and thus increase its concentration. A slight pressure is desirable to minimize the loss of volatile materials like hexamethylenediamine. Upon reaching the desired concentration, typically in the range of 70-90% by weight, the reaction mixture is transferred through a transfer line to an autoclave, which is a high pressure reactor. The reaction mixture is maintained under an oxygen-free atmosphere to avoid undesirable side reactions such as oxidative degradation. While in the autoclave, the reaction mixture is heated to a temperature between about 175° C. and about 200° C., while increasing the pressure to about 300 psia to again minimize loss of volatile organic compounds. Oligomers are formed during this stage, which generally takes about an hour. The temperature is then increased to between about 250° C. and 310° C., and the pressure is released at a slow rate to bleed off steam and thus drive the condensation reaction towards polymerization. While maintaining approximately the same temperature, the reaction mixture is held at a low constant pressure for sufficient time to obtain the desired extent of reaction. The polyamide is then extruded from the reaction vessel and conveniently chopped and dried to produce flake. The relative viscosity (RV) from the autoclave of both nylon 6,6 homopolymer and the inventive material can be in the range of 15 to 80, but is generally between 20 and 55.
The polyamide flake thus produced can be spun at the RV at which it is produced, or it can be further polymerized to a higher RV by conventional solid phase polymerization processes. Alternatively, the RV can be increased by other means such as by venting off water as the polymer is melted in the extruder prior to spinning.
Additives and modifiers may be added to the reaction mixture through inlet ports in the evaporator, the transfer line, or the autoclave. Modifiers, such as ethyleneoxide or propyleneoxide, can be used, for example, to modify polymer and/or fiber adhesion to other substrates, dyeability and RV (relative viscosity).
This allows for an in situ terminal primary amine modification, which in turn allows for the production of modified polyamides, for example. These modifiers are generally added at concentrations of about 0.01% to about 25% by weight, preferably between about 0.08% and 3% by weight, essentially all of which is incorporated into the polymeric product. The only essential characteristic of such a modifier is that it reacts with the amine group(s) to form a secondary amine, before the amine group reacts with an acid group to form an amide. A second embodiment is much like the first, except that instead of the modifier being added “neat”, it is premixed with an amount of hexamethylen-diamine adipate, for example, and then added to the reaction mixture at any of the points as detailed above. The final product is the same, but this embodiment allows for improved mixing and better control of added weights.
A third embodiment comprises contacting the modifier with hexamethylene diamine, which is then added to the acid (e.g., adipic acid) to form the salt.
The chemistry of this process for the in situ terminal primary amine modification is shown below where R1 and R2 are hydrogen, aliphatic, aromatic or al
E. I. Du Pont de Nemours and Company
Hampton-Hightower P.
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