Water-soluble or water-dispersible polyester sizing compositions

Abstract: A water-soluble or water-dispersible polyester resin composition, suitable for textile sizing applications, comprises a reaction product of 20-50% by weight of waste terephthalate polymer, 10-40% by weight of at least one glycol and 5-25% by weight of at least one oxyalkylated polyol. Preferred compositions also comprise 20-50% by weight of isophthalic acid. A further water-soluble or water-dispersible resin comprises a reaction product of 20-50% by weight of waste terephthalate polymer, 10-50% by weight of at least one glycol and 20-50% by weight of isophthalic acid.

Description: This invention relates to water-soluble or water dispersible polyester sizing compositions and to an aqueous solution or dispersion of a water-soluble or water-dispersible polyester resin and to a fiber, fabric or paper coated with a water-soluble or water-dispersible resin. Date et al., in U.S. Patent 4,104,222, have proposed making a dispersion of linear polyester resin by mixing linear polyester resin with a higher alcohol/ethylene oxide addition-type surface-active agent, melting the mixture and dispersing the resulting melt in an aqueous alkali solution. The products are used as coating and impregnating agents. Altenberg, in U.S. Patent 4,604,410, has proposed making etherified modified aromatic polyols by digesting scrap polyalkylene terephthalate with a low molecular weight polyhydroxy compound, containing 3-8 hydroxyl groups. A resulting intermediate is alkoxylated with 1-4 moles of ethylene oxide and/or propylene oxide. The final product is useful in making polyurethane and polyisocyanurate foams. Sperenza et al. (U.S. Patent 4,485,196) have recited reacting recycled polyethylene terephthalate scrap with an alkylene glycol to produce an intermediate, which is reacted with an alkylene oxide, such as propylene oxide. The product can be used in making rigid foams. Other methods of reacting scrap polyalkylene terephthalate with glycols or polyols are proposed by Svoboda et al. (U.S. Patent 4,048,104) and Altenberg et al. (U.S. Patent 4,701,477). References proposing the use of copolymers containing terephthalic units and units derived from alkylene and polyoxyalkylene glycols for fiber or fabric treatment include Hayes (U.S. 3,959,230), Nicol et al. (U.S. Patent 3,962,152), Wada et al. (U.S. Patent 4,027,346), Nicol (U.S. Patent 4,125,370) and Bauer (U.S. Patent 4,370,143). Marshall et al., in U.S. Patent 3,814,627, have proposed applying an ester, based on polyethylene glycol, to polyester yarn. EP-A-0 152 915 as closest state of the art relates to polyester polyols which are the hydroxyl-terminated digestion products of (A) polyalkylene terephthalate polymers and (B) polycarboxylic acid-containing polyols. These hydroxyl terminated polyols are useful in the preparation of cellular foam materials, in particular for polyisocyanurate and polyurethane foams. These foams can be prepared by mixing together organic polyisocyanates with the above polyol mixtures (and optionally further polyol), catalyst and blowing agent. Apart from recycling polyalkylene terephthalate scrap and saving energy, EP-A-0 152 915 aims at improved cellular foams having a combination of advantageous properties, including reduced friability and high thermal stability and compressive strength. Moreover, an improved method of producing these foams should also be defined. Sizing properties are not mentioned. BE-A-730 200 aims at providing starting material for solid polymers by recycling of polyester resins by depolymerisation in an extruder by means of 0.015 to 0.047 mols of a substance selected from water and a starting compound of the polyester per mol of dicarboxylic acid moieties in the polyester. The material can subsequently be polymerised with other acids or glycols to new and different polyester resins. Oxyalkylated polyols are not mentioned. An aqueous medium to dissolve or disperse the resin is not contemplated either. GB-A-1 146 641 relates to a method of manufacturing polyester resins suitable for use in the production of protective coatings, having improved chemical and thermal resistance. The resins are applicable as powders to substrates such as metal surfaces by the fluidisation method, by electrostatic spray or by any other dusting method with improved spreading properties. Therefore, polyterephthalate resins are subjected to alcoholysis with a glycol and a trihydric alcohol. The product thus obtained has mostly hydroxylic groups on the ends of the particles, and it can be cured at high temperatures with the aid of hardeners and with, if possible, the addition of accelerators. Isophthalic acid and oxyalkylated polyol are not mentioned. Object of the present invention is to provide a material suitable for sizing fibres, fabrics or paper on the basis of waste material which could be recycled in a convenient and environmentally beneficial manner, such as e.g. waste terephthalate plastic material. According to Claim 1 a water-soluble or water-dispersible polyester resin can be obtained in a two-step process involving depolymerisation of terephthalate polymer by heating with glycols and oxyalkylated polyols followed by modification of the so-obtained intermediate product with isophthalic acid within specific weight percentages and under certain temperature conditions. The water-solubility or water-dispersibility is based on the formation of resins having carboxyl function such that the resulting resins can be easily dissolved or dispersed in an aqueous solution or dispersion. Therefore, waste plastic materials, which would otherwise be discarded in landfills or other solid waste disposal facilities, can be cheaply and easily recycled in an environmentally beneficial manner. According to Examples 1 to 4 described hereinafter, water-soluble or water-dispersible sizing agents are obtained from a number of such terephthalate resins, which improve smoothness and elongation of cellulosic, polyester, polyamide and acrylic fibres and fabrics. Consequently, the various aspects of the above defined object are effectively solved by the product as defined in Claim 1. The water-soluble or water-dispersible resins are preferably made from waste terephthalate polymers, including bottles, sheet material, textile wastes and the like. The waste terephthalate plastics may be bought from recyclers and include, but are not limited to, material identified as "PET rock". The waste terephthalate can be characterized by the unit formula wherein R is the residue of an aliphatic or cycloaliphatic glycol of 2-10 carbons or of an oxygenated glycol of the formula HO(C x H 2x O) n C x H 2x OH, wherein x is an integer from 2-4 and n is 1-10. Preferably the waste terephthalate polymer is polyethylene terephthalate, polybutylene terephthalate, poly(cyclohexanedimethanol terephthalate) or a mixture thereof. The glycol with which the virgin and/or waste terephthalate polymer is reacted can be selected from among a variety of known dihydric alcohols. Preferred glycols include, but are not limited to, ethylene glycol, diethylene glycol, triethylene glycol, cyclohexanedimethanol, propylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol or mixtures thereof. Most preferably, the glycol is a mixture of diethylene glycol and neopentyl glycol. The oxyalkylated polyol is derived from any polyol, having three or more alcohol functions. Polyols include glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, erythritol, sorbitol, mannitol, other sugar alcohols or monosaccarides. The polyols are oxyalkylated with an alkylene oxide, including, but not limited, to ethylene oxide, propylene oxide, butylene oxide, amylene oxide, etc. Preferably, the oxyalkylated polyol is glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, erythritol or a monosaccharide, oxyalkylated with 5-30 moles of ethylene oxide, propylene oxide or a mixture thereof, per hydroxyl of the polyol. The water-soluble or water-dispersible polyester resins can be further reacted with 3-15 % by weight of trimellitic acid or anhydride. In making the water-soluble or water-dispersible polyesters, the waste terephthalate polymer, glycol and oxyalkylated polyol are heated above about 150° C to partially breakdown the terephthalate and then to heat the thus-produced intermediate with isophthalic acid under similar temperature conditions. A preferred product is that obtained by heating waste terephthalate polymer, glycol and oxyalkylated polyol above about 150° C to produce an intermediate product, characterized by a 15-minute clear peel, and heating the thus-obtained intermediate product with isophthalic acid at a temperature of at least 150° C. A most preferred water-soluble or water-dispersible polyester resin is obtained by reacting 20-50 % by weight of polyethylene terephthalate, 10-30 % by weight of diethylene glycol, 1-10 % by weight of pentaerythritol, 5-25 % by weight of oxyalkylated glycerol of 5-30 oxyalkyl units per hydroxyl, 20-50 % by weight of isophthalic acid and 3-15 % by weight of trimellitic acid or trimellitic anhydride. A highly preferred water-soluble or water-dispersible polyester resin is obtained by reacting 25-40 % by weight of polyethylene terephthalate, 20-30 % by weight of diethylene glycol, 1-10 % by weight of pentaerythritol, 5-15 % by weight of oxyethylated glycerine having 5-30 oxyethylene units per hydroxyl, 20-30 % by weight of isophthalic acid and 5-10 % by weight of trimellitic acid or trimellitic anhydride. The polyester resins are usually and preferably made using an ester-interchange catalyst. These catalysts are well known organometallic compounds, particularly compounds of tin or titanium. Preferred catalysts include tetraalkyl titanates, in which the alkyl is of up to 8 carbon atoms, as well as alkyl stannoic acids or dialkyl tin oxides, such as monobutyl stannoic acid or dioctyl tin oxide. Preferred catalysts include monobutyl stannoic acid and tetrapropyl or tetrabutyl titanate, or a mixture thereof. The resinous products obtained can be dissolved or dispersed in water with an alkali metal or ammonium hydroxide or carbonate to the desired concentration. The concentration of material to be applied to fiber, fabric or paper can readily be determined by routine experimentation. However, preferably, the solution or dispersion of water-soluble or water-dispersible resin being applied contains 0.5-5 % of resin solids. The compositions of this invention are used as sizing materials for fibers, fabrics or paper. In the textile industry, yarns are often sized before incorporation into woven or nonwoven fabrics. Sizing consists of depositing a desired amount of sizing material onto the yarn. Sizing increases the tensile strength of yarns and, in some cases, reduces yarn-to-metal coefficient of friction. Strengthening yarn is desirable in order to minimize breakage in subsequent operations, such as weaving. A low yarn-to-metal coefficient of friction decreases yarn and machine wear. Sizing materials can also be applied to fabrics. These fabrics are known as loom finished goods. The treated fabrics, after removal from the loom, before any further washing steps, have a hand which is influenced by the characteristics of the fiber, of the fabric and by the type and amount of sizing on the fabric. The products of this invention are useable when a water-soluble sizing is acceptable. Sizing compositions are normally applied to paper in a size press. The paper sheet is semi-dried and is run through the dam of a sizing solution at high speed. The paper is then run through press rolls under a high nip pressure and the treated sheet is dried under a dryer. Surface sizing is often considered superior to internal sizing because most of the sizing solution is retained on the paper. In the following examples, the temperatures are set forth uncorrected in degrees Celsius. Unless otherwise indicated, all parts and percentages are by weight. Example 1 Preparation of Water-soluble Resin from Scrap Polyethylene Terephthalate The following ingredients are used: parts by weight 19.05 diethylene glycol 5.04 neopentyl glycol 2.18 pentaerythritol 11.01 ethoxylated glycerine (17-19 moles of ethylene oxide, molecular weight 850, Witco Chemical Co., Witconol 4073) 0.08 monobutyl stannoic acid 30.47 scrap polyethylene terephthalate 25.87 isophthalic acid 6.2 trimellitic anhydride 0.1 tetrapropyl titanate The alcohols are charged to a reaction vessel and heated to 200° C to remove water. Titanate catalyst is charged to the hot alcohol mixture, after which PET is added in three batches. The initial third of the PET is added to the alcohols at 200° C, whereupon the temperature in the reactor is increased to 240° C and maintained at 240° C for 15 min. Half of the remaining PET is added and the temperature is kept at 240° C for 15 min more, after which the remaining third of the PET is added. The temperature in the reactor is kept at 240° C until a 15-minute clear peel is obtained. Clear peel time is determined by placing a drop of the reaction mixture on a Petri dish and starting a timer. The time at which the drop becomes opaque is the limit of the clear peel. When the 15-minute clear peel is obtained, the temperature in the reactor is reduced to 185° C and monobutyl stannoic acid and then isophthalic acid are charged to the reactor. The resulting mixture is heated until an acid value of 15-20 is obtained. The resulting mixture is cooled to 180° C and the trimellitic anhydride is charged to the reactor. At the end of 30 minutes, all of the trimellitic anhydride has reacted. The resulting resinous mixture is dissolved to a level of 25% solids in aqueous ammonia solution. Example 2 Preparation of Water-soluble Resin from Scrap Polybutylene Terephthalate The following materials are used: parts by weight 20.0 triethylene glycol 5.0 neopentyl glycol 2.5 trimethylolpropane 11.5 ethoxylated trimethylolpropane (10 moles of ethylene oxide) 0.1 monohexyl stannoic acid 29.5 scrap polybutylene terephthalate 30.0 isophthalic acid 1.0 tetra(isopropyl) titanate The PBT is broken down as in Example 1 to produce a resinous material, which is taken up in dilute sodium hydroxide solution to produce a stable dispersion. Example 3 Preparation of Water-soluble Resin from Scrap Poly(cyclohexanedimethanol Terephthalate) The following ingredients are used: parts by weight 25.0 ethylene glycol 20.0 ethoxylated pentaerythritol (15 moles of ethylene oxide) 30.0 scrap poly(cylohexanedimethanol terephthalate) 24.8 isophthalic acid 0.2 tetrabutyl titanate The procedure of Example 1 is followed. The resinous product obtained is dissolved in aqueous KOH solution, to a solids content of 20%. Example 4 Preparation and Use of Sizing Dispersions The products of Examples 1-3 are diluted with water to solids contents of 1-3% by weight. The diluted dispersions are used to size cellulosic, polyester, polyamide and acrylic fibers and fabrics. The compositions adhere to the treated fibers or fabrics. Smoothness and elongation are improved. The diluted materials are also used for sizing paper products. Example 5 Preparation of Water-soluble Resin from Scrap Polyethylene Terephthalate The following ingredients are used: parts by weight 11.0 diethylene glycol 21.55 cyclohexanedimethanol 30.0 scrap polyethylene terephthalate 0.08 monobutyl stannoic acid 3.91 polyethylene glycol (Pluracol PEG 4000) 0.1 tetrapropyl titanate 23.36 isophthalic acid 10.0 trimellitic anhydride The glycols are charged to a reactor and heated to 200° C to remove water. Titanate catalyst is charged to the reactor, after which one third of the PET is added and the temperature in the reactor is raised to 240° C. After 15 minutes heating at this temperature, half of the remaining PET is charged to the reactor. After 15 minutes more, the rest of the PET is added. The temperature in the reactor is kept at 240° C until a 15-minute clear peel is obtained. The temperature in the reactor is dropped to 185° C. Monobutyl stannoic acid is charged to the reactor, followed by the isophthalic acid. The mixture in the reactor is cooked until an acid value of 15-20 is obtained. The temperature may be raised to 220° C during this step. The resulting product is cooled to 180° C and the trimellitic anhydride is added. After 1 hr at this temperature, all of the trimellitic anhydride has reacted. The resulting resin is ground into a coarse powder, which is blended with sodium carbonate. Example 6 Preparation of Sizing from Water-soluble Resins The product of Example 5 is taken up in water to product solutions/dispersions, containing 1-3% by weight of resin solids. The resulting solutions/dispersions are used as sizing materials for fibers, fabrics or paper. Results are similar to those of Example 4. The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

Claims: A water soluble or water dispersible polyester resin, obtainable by reacting a) 20 - 50 % by weight of virgin and/or waste terephthalate polymer, b) 10 - 40 % by weight of at least one glycol, c) 5 - 25 % by weight of at least one oxyalkylated polyol, and d) 20 - 50 % by weight of isophthalic acid in such a way that said components a), b) and c) are heated above about 150°C, and that the thus-obtained intermediate product is further heated with said component d) at a temperature of at least 150°C. A water soluble or water dispersible polyester resin according to claim 1, characterized in that said polyester resin is further reacted with 3 - 15% by weight of trimellitic acid or trimellitic anhydride. A water soluble or water dispersible polyester resin according to claim 1 or 2, characterized in that the reaction was carried out in the presence of monobutyl stannoic acid or a tetraalkyl titanate, or a mixture thereof. An aqueous solution or dispersion of a water soluble or water dispersible polyester resin according to one of the claims 1 to 3, characterized in that said polyester resin is dissolved or dispersed in water with an alkali metal or ammonium hydroxide or carbonate. An aqueous solution or dispersible of a water soluble or water dispersible polyester resin according to claim 4 characterized in that said polyester resin is diluted to a resin solids content of 0,5 - 5%. Fiber, fabric or paper coated with the water-soluble or water-dispersible resin according to one of the claims 1 to 3.

Inventors: SALSMAN ROBERT KEITH, SALSMAN, ROBERT KEITH
Applicants: SEYDEL COMPANIES INC, THE SEYDEL COMPANIES, INC.
Application year: 1990
Main classification: C08J11
IPC codes: C08G63, D06M15, C08J11