GB838412A - Process for modifying synthetic condensation polymers - Google Patents

Abstract

A process for modifying synthetic condensation polymers comprises subjecting the polymer to ionizing radiation while it is in intimate contact with a modifier consisting of at least one organic compound which when chemically bonded (as such or in the form of a polymeric structure) with the condensation polymer as a result of the irradiation causes an appreciable change in one or more of the properties of the condensation polymer. The modifier which may be dispersed, diffused or coated upon the polymer is preferably kept in an inert atmosphere or is enclosed by a polyethylene film or aluminium foil or other material which is impervious to air and water while it is being irradiated. Additionally it may be in contact with a compound having protective or antioxidant effects with respect to the polymer or the modifier or both and during irradiation temperature is preferably kept between 0 DEG and 75 DEG C., if necessary by cooling. The process is preferably carried out in the presence of calcium tungstate, zinc sulphate, metallic lead or other radiation transfer agent capable of absorbing radiation and re-admitting it in a lower form of energy. Examples of radiation dosages suitable for the invention are given. Organic modifiers used in the invention may be found among all classes of organic compounds, and may contain, besides carbon, one or more of the elements hydrogen, halogen, nitrogen, oxygen, or sulphur. Those organic compounds, the bonds of which are easily broken, as for instance chain transfer agents, are particularly preferred. They may be of low molecular weight or of high molecular weight, especially of polymeric structure. Thus there may be used alcohols, such as methanol, ethanol, laurol; glycols, such as glycerol, pentaerythritol, sorbitol, mannitol and partial esters of these polyols; ethers, such as dimethyl, diethyl and ethylmethyl ethers; glycol ethers; oxyalkylated ethers of partial esters of the polyols, such as the polyoxyethylene derivatives of fatty acid partial esters of sorbitol; polyethers, such as polyoxethylene glycol. Mercaptans, disulphides and thioethers analogous to the above; amines, such as methylamine, ethylamine, hexamethylene diamine and dodecylamine; amides of these amines formed with acids, such as formic acid, adipic acid, suberic acid and stearic acid are useful. Organic halides, such as chloromethane, chloroform, carbon tetrachloride, chloroethane and dichlorodifluoromethane, chloroethylene and dodecafluoroheptyl alcohol. The modifier may be an unsaturated compound, particularly one which may be employed to form additional polymers by vinyl polymerization, e.g. styrene, the acrylic acid esters, vinyl chloride, vinylidene chloride, vinyl acetate, the vinyl ketones, the vinyl ethers, such as divinyl ether, acrylonitrile, methacrylonitrile, methoxydodecamethyleneoxy methacrylate, 1,3-butadiene, isoprene, chloroprene, 2,3-dimethyl-1,3-butadiene, ethylene, propylene, the acetylenes, for instance phenylacetylene, the allyl esters, vinyl compounds (other than those already mentioned) containing halogen, sulphur, nitrogen or phosphorus, and the vinyl silanes. Polymers prepared from such of the above monomeric materials as are polymerizable are also suitable. The modifiers may be incorporated with the polymer before shaping, or they may be applied to the shaped articles, e.g. as solutions or in suitable cases as pure compounds, for instance by spraying, calendering, immersion, padding or exposure to vapour condensation. In suitable cases a solution of the modifier may be applied to the surface of a shaped article and the solvent flashed off before the irradiation. If desired, excess liquid may be removed before irradiation by squeezing. Synthetic condensation polymers are polymers which can be formed by polymerization with elimination of small molecules such as HCl, H2O, NaCl, NH3 and the like, such as polyamides, polyureas, polyurethanes, polyesters, polyethers, polysulphonamides and copolymers of such materials. Of particular interest are the linear polyamides which are prepared from polymerizable monoamino carboxylic acids of their amide-forming derivatives, or from suitable diamines and suitable dicarboxylic acids or amide-forming derivatives of these compounds, especially polyamides having at least one aliphatic -HCR- group in each repeating unit of the polymer molecule. Specifications 416,236, 578,079, 712,950, 730,692, 758,735, 798,340, 838,413 and U.S.A. Specifications 2,071,250, 2,071,253, 2,130,523, 2,130,948, 2,190,770, 2,321,890, 2,321,891 and 2,647,104 are referred to.ALSO:Process for modifying synthetic condensation polymers which comprises subjecting the polymer to ionizing radiation while it is in intimate contact with a modifier consisting of at least one organic compound which when chemically bonded (as such or in the form of a polymeric structure) with the condensation polymer as a result of the irradiation causes an appreciable change in one or more of the properties of the condensation polymer. The modifier which may be dispersed, diffused or coated upon the polymer is preferably kept in an inert atmosphere or is enclosed by a polyethylene film or aluminium foil or other material which is impervious to air and water while it is being irradiated. Additionally it may be in contact with a compound having protective or antioxidant effects with respect to the polymer or the modifier or both and during irradiation temperature is preferably kept between 0 DEG and 75 DEG C., if necessary by cooling. The process is preferably carried out in the presence of calcium tungstate, zinc sulphate, metallic lead or other radiation transfer agent capable of absorbing radiation and re-admitting it in a lower form of energy. Examples of radiation dosages suitable for the invention are given. Organic modifiers used in the invention may be found among all classes of organic compounds, and may contain, besides carbon, one or more of the elements hydrogen, halogen, nitrogen, oxygen, or sulphur. Those organic compounds, the bonds of which are easily broken, as for instance chain transfer agents, are particularly preferred. They may be of low molecular weight or of high molecular weight, especially of polymeric structure. Thus there may be used alcohols, such as methanol, ethanol, laurol; glycols, such as glycerol, pentaerythritol, sorbitol, mannitol and partial esters of these polyols; ethers, such as dimethyl, diethyl and ethylmethyl ethers; glycol ethers; oxyalkylated ethers of partial esters of the polyols, such as the polyoxyethylene derivatives of fatty acid partial esters of sorbitol; polyethers, such as polyoxethylene glycol. Mercaptans, disulphides and thioethers analogous to the above; amines, such as methylamine, ethylamine, hexamethylene diamine and dodecylamine; amides of these amines formed with acids, such as formic acid, adipic acid, suberic acid and stearic acid are useful. Organic halides, such as chloromethane, chloroform, carbon tetrachloride, chloroethane and dichlorodifluoromethane, chloroethylene and dodecafluoroheptyl alcohol. The modifier may be an unsaturated compound, particularly one which may be employed to form additional polymers by vinyl polymerization, e.g. styrene, the acrylic acid esters, vinyl chloride, vinylidene chloride, vinyl acetate, the vinyl ketones, the vinyl ethers, such as divinyl ether, acrylonitrile, methacrylonitrile, methoxydodecamethyleneoxy methacrylate, 1,3-butadiene, isoprene, chloroprene, 2,3-dimethyl-1,3-butadiene, ethylene, propylene, the acetylenes, for instance phenylacetylene, the allyl esters, vinyl compounds (other than those already mentioned) containing halogen, sulphur, nitrogen or phosphorus, and the vinyl silanes. Polymers prepared from such of the above monomeric materials as are polymerizable are also suitable. The modifiers may be incorporated with the polymer before shaping, or they may be applied to the shaped articles, e.g. as solutions or in suitable cases as pure compounds, for instance by spraying, calendering, immersion, padding or exposure to vapour condensation. In suitable cases a solution of the modifier may be applied to the surface of a shaped article and the solvent flashed off before the irradiation. If desired, excess liquid may be removed before irradiation by squeezing. Synthetic condensation polymers are polymers which can be formed by polymerization with elimination of small molecules such as HCl, H2O, NaCl, NH3 and the like, such as polyamides, polyureas, polyurethanes, polyesters, polyethers, polysulphonamides and copolymers of such materials. Of particular interest are the linear polyamides which are prepared from polymerizable monoamino carboxylic acids of their amide-forming derivatives, or from suitable diamines and suitable dicarboxylic acids or amide-forming derivatives of these compounds, especially polyamides having at least one aliphatic -HCR- group in each repeating unit of the polymer molecule. The polymers treated may be in the form of funicular-shaped structures such as filaments, staple fibres, and yarns comprising them; woven, knitted, felted or fused fabrics and to their films. Shaped structures to be treated may be made by extrusion, moulding, casting or calendering. The polymers may also be treated in the form of finely-comminuted particles which may subsequently be shaped, either in the molten state or in solution, e.g. by extrusion, moulding or casting. Examples of specific shaped articles which may be treated include woven or knitted fabrics, articles made from them for clothing or industrial use, reinforcement for composite structures (such as cords for mechanical rubber goods and fibre for laminates), artificial bristles or artificial straw and rods, bars, sheets, plates and laminates. Specifications 416,236, 578,079, 712,950, 730,692, 758,735, 798,340, 838,413, and U.S.A. Specifi