GB693645A - Method of increasing the molecular weight of polyesters, polyesteramides or polyamides or polyamides - Google Patents

Abstract

The molecular weight of a polyamide, polyester or polyesteramide containing at least two radicles selected from hydroxyl and amino with at least one reaction hydrogen atom, is increased by reacting the polymer with an N-acyl polylactam (see Group IV (b)) in which two or more lactams are linked by their nitrogen atoms with the acyl radical of a polycarboxylic acid. The polylactams are described in U.S.A. Specification 2,303,177. Suitable ones are N,N1-terephthalyl bis caprolactam having the formula <FORM:0693645/IV (a)/1> N,N1 - isophthalyl bis epsilon caprolactam; N,N1-adipyl bis epsilon caprolactam; N,N1-adipyl bis valerolactam; N,N1-isophthalyl bis valerolactam; N,N1-isophthalyl bis butyrolactam; N,N1 - 2,5 - dichloroterephthalyl bis caprolactam; N,N1,N11-trimethyl tris epsilon caprolactam; the tetra valerolactam of 1,4,5,8-naphthalene tetracarboxylic acid; the tetra epsilon caprolactam of cyclohexanonetetrapropionic acid or of dicyclohexanoneoctapropionic acid; and the polycaprolactam of polyacrylic acid. The invention is particularly useful for obtaining linear polymers, particularly polyesters, of high molecular weight from low polymers with terminal hydroxyl and/or amino groups. A list of ingredients which may be used for preparing such polyesters is given. By using an excess of glycol and/or diamine linear polymers with reaction terminal groups are readily produced as starting materials for the invention. They may also be prepared from an hydroxy acid, or an amino acid. The number of acylating groups arising from the polylactam is preferably equivalent to the number of hydroxy and/or amino groups in the polymer. Excess lactam may be removed under reduced pressure or the lactam may be added in small doses until reaction ceases. The reaction may be performed in a non-reactive solvent and at elevated temperature. An inert atmosphere may be employed. The polymer is recovered by precipitation or distillation of the solvent. In the examples: (2) low molecular weight poly-decamethylene sebacate, prepared with excess glycol, was refluxed in o-dichlorobenzene with N,N1-isophthalyl-bis-caprolactam; (3) molten low molecular weight decamethylene sebacate was treated with N,N1-terephthalyl-bis-caprolactam; (4) low molecular weight polyethylene terephthalate was heated in o-dichlorobenzene with N,N1-isophthalyl-bis-caprolactam; (5) polytetramethylene terephthalate with hydroxyl end groups was reacted in o-dichlorobenzene with N,N1-isophthalyl-bis-caprolactam; (6) low molecular weight polyhexamethylene terephthalate was reacted with N,N1 - terephthalyl - bis - caprolactam; (7) hydroxyl terminated polydecamethylene terephthalate was reacted with N,N1-terephthalyl-bis-caprolactam; (8) polytetramethylene isophthalate was treated with N,N1-isophthalyl-bis-caprolactam. Cross-linked polymers are obtained if one of the reactants has a functionality greater than 2. An example is the reaction of a low molecular weight polymer from decamethylene glycol, pentaerythritol and adipic acid with N,N1-isophthalyl-bis-caprolactam. The use of polycarboxylic acids with a functionality greater than 2, or of compounds with more than two lactam groups is also referred to. U.S.A. Specifications 2,524,045 and 2,524,046 also are referred to.ALSO:N-acyl polylactams in which two or more lactam groups are linked by their nitrogen atoms with the acyl radicle of a polycarboxylic acid are prepared by reacting a lactam with the acyl chloride or bromide of a polycarboxylic acid. In example 1 epsilon caprolactam and terephthalyl chloride were heated together in dioxane containing some triethylamine. Triethylamine hydrochloride was removed by filtration. The product, N-N1-terephthalyl-bis-caprolactam, was precipitated from the concentrated filtrate by treatment with ethyl acetate and recrystallization from alcohol, the di-lactam melted at 191-193 DEG C. Other polylactams mentioned are N,N1-isophthalyl-bis-caprolactam; N,N1 - adipyl - bis - caprolactam; N,N1 - adipyl - bis - valerolactam; N,N1 - isophthalyl-bis-valerolactam; N,N1-isophthalyl-bis - butyrolactam; N,N1 - terephthalyl - bis - butyrolactam; N,N1-2,5-dichloroterephthalyl-bis - caprolactam; N,N1,N11 - trimesyl - tris - caprolactam; the tetra-valerolactam of 1,4,5,8-naphthalene tetracarboxylic acid; the tetra caprolactam of cyclohexanonetetrapropionic acid; the tetra-caprolactam of dicyclohexanoneoctapropionic acid; and the polycaprolactam of polyacrylic acid. U.S.A. Specification 2,303,177 is referred to.