| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | March 27, 1984 |
| PATENT TITLE |
Polyurethane having excellent elastic recovery and elastic filament of the same |
| PATENT ABSTRACT |
A polyurethane having excellent elastic recovery is obtained by reacting an organic diisocyanate with a polycaprolactone polyester-diol prepared from a dihydric alcohol, a dibasic acid, an ester thereof or an anhydride thereof and .epsilon.-caprolactone or/and hydroxycaproic acid and having a hydroxyl value of 35 to 150 KOH mg/g and a content of .epsilon.-caprolactone and hydroxycaproic acid of 69 to 95% by weight. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | September 29, 1982 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT CLAIMS |
The embodiments of the invention of which an exclusive property or privilege is claimed are defined as follows: 1. A polyurethane having excellent elastic recovery, said polyurethane having been prepared by reacting an organic diisocyanate with a polycaprolactone polyester-diol, said polycaprolactone polyester-diol having been prepared by reacting a reaction mixture consisting essentially of (i) neopentyl glycol, (ii) a dibasic acid, an ester thereof or an anhydride thereof, and (iii) a material selected from the group consisting of epsilon-caprolactone, hydroxycaproic acid and mixture thereof, under conditions effective to form a random copolymer in which units derived from said neopentyl glycol and said component (ii) are randomly distributed in a polycaprolactone chain, said polycaprolactone polyester-diol having a hydroxyl value of 35 to 150 KOH mg/g and containing from 60 to 95% by weight of said material (iii). 2. A polyurethane as claimed in claim 1, in which said dibasic acid is adipic acid or sebacic acid. 3. A polyurethane as claimed in claim 1, in which said polycaprolactone polyester-diol has a hydroxyl value of 40 to 60 KOH mg/g and contains from 65 to 90% by weight of said material (iii). 4. A spandex fiber made by spinning a polyurethane as claimed in claim 1. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
The invention relates to polyurethane having excellent elastic recovery and elastic filament of the same and furthermore production of them. Heretofore, linear polyurethanes have been synthesized by reacting a long-chain polyol having hydroxyl groups on both molecular terminals with an organic diisocyanate and a relatively low-molecular weight compound having two active hydrogen atoms, called a chain extender, such as a diamine or an alkanolamine. The long-chain polyol having hydroxyl groups on both molecular terminals chiefly used is a polyester-polyol or a polyether-polyol. The polyester-polyol generally used includes a polyester-polyol synthesized from adipic acid and ethylene glycol, 1,4-butylene glycol, 1,6-hexane glycol or the like or a polycaprolactone-polyol obtained from .epsilon.-caprolactone. The polyether-polyol used includes a polymer or copolymer of ethylene oxide or propylene oxide or a polytetramethylene glycol as a polymer of tetrahydrofuran. Among these, the polyether-polyol, particularly, polytetramethylene glycol is widely used in the fields of articles such as spandex, that is, elastic fiber, and urethane elastomers required to have low compression permanent set, because the glycol has excellent water resistance and also because polyurethanes made from the glycol possess excellent recovery. However, the polyether-polyols have a defect that their weather resistance and heat resistance are extremely poor because of their susceptibility to oxidative degradation. On the other hand, polyurethanes prepared from ethylene glycol adipate polyester as a polyester-polyol are excellent in elastic recovery but poor in water resistance and accordingly products from the polyester have a defect that they become useless within one year or two. Moreover, 1,4-butylene glycol adipate polyester has water resistance in some degree, but urethanes derived therefrom have extremely poor elastic recovery. Furthermore, polyurethanes made from a polycaprolactone-polyol derived from .epsilon.-caprolactone have a feature that they are not only excellent in water resistance but also extremely excellent in weather resistance and heat resistance, deficiency of which is a defect of the polyether-polyols. In spite of such a feature, the polyurethanes have not been used in the field of spandex, etc., because of a defect that their elastic recovery is very poor. As a result of eager studies to eliminate such a defect of polycaprolactone urethane, the inventors of this invention have found that polyurethanes made from polycaprolactone polyester-polyol synthesized from a polyhydric alcohol, a polybasic acid and .epsilon.-caprolactone or hydroxycaproic acid show an excellent elastic recovery not found in conventional polyurethanes and have reached this invention. Namely, this invention provides a polyurethane prepared by using, as a compound having two active hydrogen atoms in the molecule in producing a polyurethane by reacting an organic diisocyanate with said compound, a polycaprolactone polyester-diol prepared from a dihydric alcohol, a dibasic acid, an ester thereof or an anhydride thereof and .epsilon.-caprolactone and/or hydroxycaproic acid and having a hydroxyl value of 35 to 150 KOH mg/g and a content of .epsilon.-caprolactone and hydroxycaproic acid of 60 to 95% by weight and having an elastic recovery of at least 50%, preferably at least 70% and a process for producing the same. The OH value is measured according to Japan Industrial Standard (JIS) K-1557, 6.4. The elastic recovery as used herein is a value calculated from the following expression. That is, a % recovery (at 25.degree. C.) shown by a polyurethane when it is stretched 300% its original length and, after relaxation of the strain, is allowed to stand for 10 minutes. ##EQU1## wherein l: length between indication lines before stretch l': length between indication lines after stretch and relaxation of strain. The dihydric alcohols as starting materials for the above polycaprolactone polyester-polyols used in this invention include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 2-methyl-1,3-propanediol, 1,5-pentyl glycol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, hydroxypyruvic acid ester of neopentyl glycol, 2,3,5-trimethylpentanediol, and AOG.times.24 (trade name, a mixture of C.sub.12 and C.sub.14 .alpha.-olefin glycols produced by Daicel Ltd.). Neopentyl glycol is preferable. A combination of combination of neopentyl glycol and another diol such as ethylene glycol and 1,4-butylene glycol may be used. As the dibasic acids, an ester thereof or an anhydride thereof there can be used maleic acid, succinic acid, fumaric acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, phthalic acid, isophthalic acid, terephthalic acid, hexahydrophthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, and anhydrides thereof. Adipic acid and sebacic acid are preferable. As the third material, .epsilon.-caprolactone, there can be used one which is industrially manufactured by oxidizing cyclohexanone with hydrogen peroxide or a peracid such as peracetic acid according to a Bayer-Biliger reaction. Moreover, unless the feature of this invention is not adversely affected, lactones or hydroxy acids other than .epsilon.-caprolactone and hydroxycaproic acid can be used in combination with .epsilon.-caprolactone. The polycaprolactone polyester-diol synthesized from a dihydric alcohol, a dibasic acid or an ester thereof and .epsilon.-caprolactone or hydroxycaproic acid has an OH value of 35 to 150 KOH mg/g, preferably 40 to 100, more preferably 40 to 60, and a content of .epsilon.-caprolactone and hydrocaproic acid of 60 to 95% by weight, preferably 65 to 90% by weight. The polycaprolactone polyester-diols can be synthesized by heating, with stirring, a dihydric alcohol, a dibasic acid and .epsilon.-caprolactone or hydroxycaproic acid and effecting a dehydration/esterification reaction and a ring-opening reaction or an ester inter-change reaction. It is also possible to obtain the desired product by mixing a polyester-diol synthesized by a dehydration/esterification reaction between a dihydric alcohol and a dibasic acid with a polycaprolactone-diol synthesized by a ring-opening reaction of .epsilon.-caprolactone and effecting an ester interchange reaction between them. Moreover, it can also be synthesized by subjecting 4-caprolactone and a low-molecular weight polyester-diol to a ring opening polymerization. These reactions are carried out at 130.degree. to 240.degree. C., preferably 140.degree. to 230.degree. C. Temperatures higher than 250.degree. C. not only adversely affects the color of the resulting resin but also cause depolymerization of the polycaprolactone. Accordingly, it is impossible to obtain the desired product. In this reaction, 0.05 to 1,000 ppm, preferably 0.1 to 100 ppm of a catalyst is used. As the catalysts there can be used organotitanium compounds such as tetrabutyl titanate, tetrapropyl titanate and tin compounds such as dibutyltin laurate, tin octoate, dibutyltin oxide, stannous chloride, stannous bromide and stannous iodide. To prevent coloration of the resin it is preferable that the reaction is carried out under a stream of an inert gas such as nitrogen. As the organic diisocyanates used in the production of the polyurethane of this invention there can be mentioned 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate and 1,5-naphthylene diisocyanate. As the low-molecular weight compounds having active hydrogen atoms of this invention, called a chain extender, there can be used ethylene glycol, propylene glycol, 1,4-butylene glycol, 2-methyl-1,3-propanediol, neopentyl glycol, pentanediol, 1,6-hexanediol, ethylenediamine, propylenediamine, hydrazine, isophoronediamine, m-phenylenediamine, 4,4'-diaminodiphenylmethane, diaminodiphenyl sulfone and 3,3'-dichloro-4,4'-diaminodiphenylmethane. As the production process of the polyurethane of this invention there can be used any of the following processes: a prepolymer process in which a diol and an excess of an organic diisocyanate are reacted to produce a prepolymer having isocyanato groups on both terminals and, then the prepolymer is reacted with a chain extender such as a diol or a diamine to produce a polyurethane or a one-shot process in which all of the components are added at once to form a polyurethane. These polyurethane production processes can be carried out in the presence or absence of a solvent. As the solvents there are employed those inert to an isocyanate. For example, there are used toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, dimethylformamide and tetrahydrofuran. The polycaprolactone polyester-diol type urethane of this invention is excellent not only in water resistance, weather resistance and heat resistance but also excellent in elastic recovery as compared with conventional polyurethanes. The reason for this can be interpreted as follows: because the dibasic chain and the dihydric chain constituting polyester chains are randomly, partially interposed in between the molecular chains of the polycaprolactone-diol, the crystallinity of the polycaprolactone is somewhat disturbed and this strengthens further the structure of crystalline crosslinking sites which are repeating portions consisting of the chain extender of the polyurethane and the diisocyanate. The polyurethane of this invention can be used extremely advantageously in spandex, thermoplastic urethane elastomers, thermosetting urethane elastomers, rigid and flexible urethane foams, adhesives, artificial leathers, synthetic leathers, paints, or the like. In particular, the polyurethane elastic filament according to the invention will be illustrated below. The structure of the polycaprolactone polyester diol of the present invention obtained by these synthesis reactions is different from that of a perfect block copolymer consisting of polycaprolactone and polyester chains prepared by the ring-opening polymerization of caprolactone with terminal hydroxyl group(s) of a polyester diol obtained from a dihydric alochol and a dibasic acid. Rather, this polymer has a random copolymer structure wherein residues of the dihydric alcohol and dibasic acid are distributed at random in a polycaprolactone chain by the interesterification reaction. This fact is proved by the fact that if a block copolymer obtained by the ring-opening polymerization of a polyester diol comprising a dihydric alcohol and a dibasic acid with .epsilon.-caprolactone is further heated, its melting point and melt viscosity are gradually reduced to attain definite values. Namely, the block copolymer is converted into the random copolymer by the interesterification reaction to reduce its crystallizability. Furthermore, stabilizers for the polyurethane elastic filament, such as conventional antioxidant, U.V. absorber, mildew-proofing agent, heat deterioration inhibitor and hydrolysis inhibitor, as well as a filler such as titanium oxide and a pigment may be added. Particularly, the addition of a hydrolysis inhibitor such as a carbodiimide compound, e.g. Stabaxol I or P (trade names of Farbenfabriken Bayer AG), is effective. The polyurethane elastic filament according to the invention may be produced by conventional spinning methods, such as the wet method, the dry method and the melting method. The filament can be made into a fabric by itself or in combination with other fibers. Female garments such as stockings, brassieres, shorts and foundations and industrial elastic fabrics can be made from the filament according to the invention. This invention will now be illustrated with reference to examples and a comparative example, though it should be noted that this invention is not limited by these examples. In these examples parts are given by weight. |
| PATENT EXAMPLES | available on request |
| PATENT PHOTOCOPY | available on request |
|
Want more information ? Interested in the hidden information ? Click here and do your request. |