MXPA99008938A

MXPA99008938A - Process for producing polyurethane elastomer and elastic filament

Info

Publication number: MXPA99008938A
Application number: MXPA/A/1999/008938A
Authority: MX
Inventors: Tsutsumi Nobuhisa; Tamura Kenji; Yoshimoto Mitsuhiko
Original assignee: Nisshinbo Industries Inc
Filing date: 1999-09-28
Publication date: 2000-12-06

Abstract

A process for producing a polyurethane elastomer or elastic filament, wherein a first polymer diol of a molecular weight of at least 600, a second polymer diol of a molecular weight of at least 600, a first low molecular weight diol having a molecular weight of not higher than 500, a second low molecular weight diol, a first diisocyanate and a second diisocyanate are used as the main starting materials, and the molar ratio of the total of the first diisocyanate and the second diisocyanate in the starting materials to the total of the first polymer diol, the second polymer diol, the first low molecular weight diol and the second low molecular diol is 0. 95 1 to 1.25 1, characterized in that a fluid polyurethane (obtained by continuously reacting a prepolymer having a terminal hydroxyl group and obtained by reacting the first polymer diol, the first low molecular weight diol and the first diisocyanate with a prepolymer having a terminal isocyanate group and obtained by reacting the second polymer diol, the second low molecular weight diol and the second diisocyanate) is continuously extruded through a nozzle.

Description

PROCESS FOR PRODUCING ELASTOMER OF POLYURETHANE AND FILAMENT THE STICO DESCRIPTION OF THE INVENTION The present invention relates to a process for producing a polyurethane elastic material, especially elastic yarn, by a reaction spinning method. It is known that an elastic polyurethane material is produced by an extrusion molding method using thermoplastic polyurethane pellets, produced by a polymeric diol, a diisocyanate and a low molecular weight diol. However, since parts of the bonds in the polymer are decomposed during extrusion molding, a polyurethane elastic material having satisfactory thermal properties such as permanent residual bonding after elongation in a high temperature environment, especially the Polyurethane yarn having excellent thermal properties, can not be obtained by this method. Methods of reaction yarns are also known in order to improve the thermal properties of the polyurethane elastic yarn by a melt spinning method, such as a method in which the polymeric diol, a diisocyanate and a low molecular weight diol are they polymerize by a one-pass process and the yarn is spun directly from this polymerization system, another method in which a prepolymer having an isocyanate terminal is reacted with a low molecular weight diol, and the yarn is spun directly from this reaction system. The elastic materials obtained by these reaction spinning methods are superior in thermal properties than an elastic material produced from pellets, by a melt spinning method due to the low thermal history of the polymer. That is, in the melt spinning method using pellets, an isocyanate that remains in the pellets after synthesis reacts with the water contained in the air to form a urea group or a three-dimensional bond by the reaction of an allophanate or a burette The urea group and the three dimensional bond improves the thermal properties of the polymer, it breaks down during extrusion molding. It should be noted that the elastic material obtained by a spinning method by reaction can retain excellent thermal properties because the urea group and the three dimensional bond remain in the polymer as they are. However, since the reaction spinning method itself tends to spin unstable polymer that is incomplete and in the course of synthesizing the polymer, it is inferior in spinning capacity. In addition, because a reagent is reacted with another reagent that differs greatly in viscosity and volume ratio while mixing together, a large number of abnormal reaction products is easily introduced, by uniform mixing and is difficult to safely measure the trace components, so that the stability of the yarn is damaged and it is also difficult to obtain uniform polyurethane elastic yarn, especially small denier polyurethane elastic yarn. In order to further improve the thermal properties of a polyurethane elastic material produced by a reaction spinning method, it is generally effective to increase the molar ratio of a diisocyanate to the total of the polymeric diol and a low molecular weight diol. However, when the molar ratio of the diisocyanate is increased, the molecular weight of a polyurethane polymer does not become high enough-at the time of spinning, resulting in reduced spinnability. Therefore, the inventors of the present invention have proposed a method for improving the spinnability by adding a special additive such as a dimer of diisocyanate or fine powdered silica to carry out a spinning reaction method to obtain an elastic yarn. of polyurethane of a prepolymer having an isocyanate terminal and a low molecular weight diol (Japanese Patent Publication Nos. 63-53287 and 63-53288). Nevertheless, this method has a problem with the uniform dispersibility of these additives and problems such as a complicated process and difficulty in selecting the mixing conditions at the time of a reaction. A method for obtaining an elastomer such as a pellet by reacting a mixture of a polymeric diol and a low molecular weight diol in an amount of 1 to 3 times the molar amount of the polymeric diol with an isocyanate to give a prepolymer is also known. has a hydroxyl terminal and a prepolymer having an isocyanate terminal and then reacting the two in order to reduce a difference in viscosity between the prepolymer having a hydroxyl terminal and the prepolymer having an isocyanate terminal so as to form a good condition of mixing (Japanese Patent Publication No. 43-639). However, the elastomer obtained by this method is an elastomer for melt spinning which is melted and spun in the yarn and it is not described in the above publication that spinning is carried out by reacting the raw material continuously such as the polyols . It is an object of the present invention to solve the drawbacks of the prior art mentioned above and to provide a process for stably producing a polyurethane elastic material having excellent thermal properties, especially elastic yarn, by a spin-by-reaction method.

That is, the present invention is a process for producing polyurethane elastic yarn from a first polymeric diol having a molecular weight of 600 or more, a second polymeric diol which can be the same or different from the first polymeric diol and has a weight molecular weight of 600 or more, a first low molecular weight diol having a molecular weight of 500 or less, a second low molecular weight diol which may be the same as or different from the first low molecular weight diol, a first diisocyanate and a second diisocyanate can be the same or different from the first diisocyanate as the main starting material, the total molar amount of the first diisocyanate and the second diisocyanate in the starting materials being 0.95 to 1.25 times the total molar amount of the first polymeric diol, the second polymeric diol , the first diol of low molecular weight and the second diol of low molecular weight, comprising the steps of: continuously extruding from a nozzle a pol liquid polyurethane group obtained by reacting a prepolymer having a hydroxyl terminal obtained by reacting the first polymeric diol, the first low molecular weight diol and the first diisocyanate with a prepolymer having isocyanate terminal obtained by reacting the second polymeric diol, the second diol of low molecular weight and the second diisocyanate.

In the above production process, the second low molecular weight diol is preferably used in a molar amount less than 1.0 times the molar amount of the second polymeric diol. The present invention is also a process for producing a polyurethane elastic material of a first polymeric diol having a molecular weight of 600 or more, a second polymeric diol which can be the same or different from the first polymer diol and has a molecular weight of 600 or more, a first low molecular weight diol having a molecular weight of 500 or less, a second low molecular weight diol which can be the same or different from the first low molecular weight diol, a first diisocyanate and a second diisocyanate which can be the same as or different from the first diisocyanate as main starting materials, the total molar amount of the first diisocyanate and the second diisocyanate in the starting materials being 0.95 to 1.25 times the total molar amount of the first polymeric diol, the second polymeric diol, the first diol of low molecular weight and the second diol of low molecular weight, and the molar amount of the second diol of low molecular weight is less than 1.0 times the molar amount of the second polymeric diol, the steps comprising: continuously extruding from a nozzle a polyurethane polymer in a fluid state obtained by reacting a prepolymer having a hydroxyl terminal obtained by reacting the first polymeric diol, the first diol of low molecular weight and the first diisocyanate with a prepolymer having an isocyanate terminal obtained by reacting the second polymeric diol, the second low molecular weight diol and the second diisocyanate. The present invention is furthermore a process for producing polyurethane elastic yarn of a first polymeric diol having a molecular weight of 600 or more, a second polymeric diol which can be the same or different from the first polymeric diol and has a molecular weight of 600 or more. more, a low molecular weight diol having a molecular weight of 500 or less, a first diisocyanate and a second diisocyanate which may be the same or different from the first diisocyanate as the main starting materials, the total molar amount of the first diisocyanate and the second diisocyanate in the starting materials, being 0.95 to 1.25 times the total molar amount of the first polymeric diol, the second polymeric diol and the low molecular weight diol, the steps comprising: continuously extruding from a nozzle a polyurethane polymer in a liquid state obtained by reacting a prepolymer having a hydroxyl terminal obtained by reacting the first diol polymeric, the first low molecular weight diol and the first diisocyanate with a prepolymer having an isocyanate terminal obtained by reacting the second polymeric diol, and the second diisocyanate. The present invention is furthermore a process for producing a polyurethane elastic material of a first polymeric diol having a molecular weight of 600 or more, a second polymeric diol which can be the same or different from the first polymeric diol and has a molecular weight of 600. or more, a low molecular weight diol having a molecular weight of 500 or less, a first diisocyanate and a second diisocyanate which may be the same or different from the first diisocyanate as the main starting materials, the total molar amount of the first diisocyanate and the second diisocyanate in the starting materials, being 0.95 to 1.25 times the total molar amount of the first polymeric diol, the second polymeric diol and the low molecular weight diol, the steps comprising: continuously extruding from a nozzle a polyurethane polymer in a liquid state obtained by reacting a prepolymer having a hydroxyl terminal obtained by reacting the first polymer diol, the low molecular weight diol and the first diisocyanate with a prepolymer having the isocyanate terminal obtained by reacting the second polymeric diol, and the second diisocyanate. In this description, unless stated otherwise, the "polymeric diol" means a polymeric diol having a molecular weight of 600 or more, and the "Low molecular weight diol" means a diol having a molecular weight of 500 or less. In the above production process of the present invention, preferably, the prepolymerb having the hydroxyl terminal is obtained by reacting the first polymeric diol in an amount of 60 to 10 mol% based on the total amount of the first polymeric diol and the second polymer diol, the first diisocyanate in an amount of 1.3 to 2.5 times the molar amount of the first polymeric diol and the first low molecular weight diol in an amount of 2 times or more the molar amount of the first polymeric diol, and the prepolymer having the isocyanate terminal is obtained by reacting the second polymeric diol in an amount of 90 to 40 mol% based on the total amount of the first polymeric diol and the second polymeric diol and the second diisocyanate in an amount 2 times or more the molar amount of the second polymeric diol. In the production process of the present invention, the prepolymer having the hydroxyl terminal is preferable obtained by reacting the first polymeric diol and the first diisocyanate to give a first precursor and then reacting the precursor and the low molecular weight diol. Further, when the second polymeric diol, the second diisocyanate and the second low molecular weight diol are used to produce the prepolymer having the isocyanate terminal, the prepolymer having the hydroxyl terminal is preferably obtained by reacting the first polymeric diol and the first diisocyanate to give a first precursor and then react the first precursor and the first low molecular weight diol, and the prepolymer having an isocyanate terminal is preferably obtained by reacting the second polymeric diol and the second diisocyanate to give a second precursor and then reacting the second precursor and the second low molecular weight diol in an amount less than 1.0 times the molar amount of the second polymeric diol. In the production process of the present invention, preferably the first polymeric diol and the second polymeric diol, each is selected from the group consisting of polyether diols and polyester diols. Further, in the production process of the present invention, preferably, the first polymeric diol is a polyether diol and the second polymeric diol is a polyester diol.

The present invention also provides an elastic polyurethane and elastic yarn material produced by the above process. The present invention will be described in detail below. The most important point for spinning an elastic material of polyurethane or elastic yarn (which may be referred to as "elastic material or the like" hereinafter) of a polymerization system is directly realized in an ideal state of mixing in consideration of the reactivity of each one of the reagents. Especially, when a polyurethane formed from a polymeric diol, a diisocyanate and a low molecular weight diol is spun directly into elastic yarn of a polymerization system, a sufficient mixing effect can not be expected from the point of view of the ratio of viscosity and volume of each of the reagents as described above even using any of a one-pass process, a conventional prepolymer process in which a prepolymer having an isocyanate terminal with a molecular weight level is reacted low (which may be referred to as "conventional prepolymer process" hereafter) and a process in which an additive such as fine powdered silica is used. Since there are many opportunities for a diisocyanate to react with a low molecular weight diol in a non-uniform mixed state, an abnormally reacting product is easily formed and it is difficult to accurately measure the trace components. As a result, such a problem as the lack of stability Spinning is still not essentially solved. It is desired that an ideal mixing state with few abnormal reactions be carried out taking into account the viscosity and volume ratio of each of the reactants to produce an elastic material and an elastic yarn. The inventors of the present invention have carried out intensive studies to solve the above problem and have succeeded in improving the reaction uniformly and spinning an elastic material of polyurethane and elastic yarn having excellent thermal stability without special additivescontinuously extruding from a nozzle a polyurethane polymer in the fluid state obtained by continuously reacting two different prepolymers having almost the same volume and relatively close viscosity with one another, and discovering the ideal conditions for mixing the two different prepolymers in order to achieve the present invention. One of the two different prepolymers is a prepolymer having a hydroxyl terminal obtained by reacting the first polymeric diol, the first low molecular weight diol and the first diisocyanate. The other prepolymer is a prepolymer having an isocyanate terminal obtained by reacting the second polymeric diol, the second low molecular weight diol and the second diisocyanate. The first polymeric diol and the second polymeric diol can be the same or different. The first low molecular weight diol and the second low molecular weight diol can be the same or different. In addition, the first diisocyanate and the second diisocyanate can be the same or different. In the production process of the present invention, the total molar amount of the first diisocyanate and the second diisocyanate is 0.95 to 1.25 times, preferably 1.03 to 1.15 times the total molar amount of the first polymeric diol, the second polymeric diol, the first diol of low molecular weight and the second diol of low molecular weight. If the ratio of the total amount of the first diisocyanate and the second diisocyanate to the total molar amount of the first polymeric diol, the second polymeric diol, the first low molecular weight diol and the second low molecular weight diol meet the above requirement, the The weight ratio of the polymeric diols, the diisocyanates and the low molecular weight diols in the polyurethane elastic material or the like, can be changed in a varied manner according to the molecular weight of each of the above components and the desired properties of the elastic material. As for the weight ratio of the components of the starting materials to obtain the prepolymer having the hydroxyl terminal, the amount of the first polymeric diol is preferably 60 to 10 mol%, particularly preferably 50 to 15 mol% based on the total amount of the first and second polymeric diols, the amount of the first diisocyanate is preferably 1.3 to 2.5 times, particularly preferably 1.8 to 2.1 times the molar amount of the first polymeric diol and the amount of the first diol of weight Low molecular weight is preferably 2 times or more, particularly 4 times or more depreference the molar amount of the first polymeric diol. On the other hand, regarding the proportion by weight of the components of initial materials to obtain the prepolymer having the isocyanate terminal, the amount of the second polymeric diol is preferably 90 to 40 mol%, particularly preferably 85 to 50 mol. % molar, based on the total amount of the first and second polymeric diols, the amount of the second diisocyanate is preferably 2 times or more, particularly preferably 3 times or more the molar amount of the second polymeric diol and the amount of the second diol of Low molecular weight is preferably less than 1.0 times or less, particularly preferably 0.5 times or less the molar amount of the second polymeric diol. When the amount of the first polymeric diol used in the hydroxyl terminal prepolymer is 60% molar-O- more based on the total amount, the viscosity of the prepolymer having the hydroxyl terminal is generally high at 10,000 cP or more (at a temperature of 70 ° C, the lower viscosity figures are values at 70 ° C unless stated otherwise and the viscosity of the prepolymer having the isocyanate terminal is generally low at 80 cP or less. polymeric diol used in the prepolymer having the hydroxyl terminal is 10 mol% based on the total amount, the viscosity of the prepolymer having the hydroxyl terminal is generally low at 500 cP or less and the viscosity of the prepolymer having the isocyanate terminal is generally high at 5,000 cP or more. Any case does not have a good influence on the state of mixing of the two different prepolymers: the prepolymer having the hydroxyl terminal and the prepolymer having the isocyanate terminal. When the amount of the second low molecular weight diol used in the isocyanate terminal prepolymer is 1.0 times or more the molar amount of the second polymeric diol, the viscosity of the prepolymer having the isocyanate terminal is generally high at 20,000 cP or more, which tends to have a difference greater than the viscosity of the prepolymer having the hydroxyl terminal. This difference does not exert such a good influence on the state of mixing of the two different prepolymers. Therefore, the amount of the second low molecular weight diol is preferably less than 1.0 times the molar amount of the second polymeric diol. When the stability of spinning is given special importance, the amount of the second low molecular weight diol is more preferably 0.5 times or less the molar amount of the second polymeric diol. In addition, it may be chosen whether or not to mix the second low molecular weight diol. The mixing ratio of the diisocyanates in the two different prepolymers has a greater influence on the formation of an abnormal reaction product at the time of synthesizing the prepolymer having the hydroxyl terminal and the viscosity of the prepolymer having the hydroxyl terminal. When the amount of the first diisocyanate used in the prepolymer having the hydroxyl terminal is greater than 2.5 times the molar amount of the first polymeric diol used in the hydroxyl terminal prepolymer, an abnormal reaction product formed by reacting the first diol of low molecular weight and the first diisocyanate, is formed in the prepolymer having the hydroxyl terminal, whereby the spin stability tends to deteriorate. On the other hand, when the amount of the first diisocyanate used in this prepolymer having the hydroxyl terminal is less than 1.3 times the molar amount of the first polymeric diol used in the prepolymer having the hydroxyl terminal, the viscosity of the prepolymer having the Hydroxyl terminal becomes as high as 10,000 cP or more at 70 ° C, so the mixed state of the prepolymer having the isocyanate terminal and the prepolymer having the hydroxyl terminal becomes worse and does not have good influence on the spinning stability. The prepolymer having the hydroxyl terminal and the prepolymer having the isocyanate terminal can be obtained by mixing and stirring any kind of starting material components at a predetermined reaction temperature for a predetermined reaction time. More specifically, the polymer diol, the diisocyanate and the low molecular weight diol can be reacted with one another by a one-step process. A more effective process includes a stepwise reaction process comprising the steps of reacting a polymer diol with a diisocyanate to form a precursor containing a prepolymer having an isocyanate terminal and then reacting the obtained precursor with a diol. of low molecular weight in order to form a prepolymer having a terminal and hydroxyl or a prepolymer having an isocyanate terminal. In the case of the prepolymer having a hydroxyl terminal, for example, this step-wise process is carried out by reacting the first polymeric diol in an amount of 60 to 10 mol% based on the total amount of the first and second diols polymeric with the first diisocyanate in an amount of 1.3 to 2.5 times the molar amount of the polymeric diol to give a first precursor and then reacting the first precursor with a first low molecular weight diol in an amount of 2 times or more the molar amount of the first polymeric diol. In the case of the prepolymer that has the isocyanate terminal, for example, this process is carried out by reacting the second polymeric diol in an amount of 90 to 40 mol% based on the total amount of the first and second polymeric diols with the second diisocyanate in an amount 2 times or more the amount molar of the second polymeric diol to give a second precursor and then reacting the second precursor with the second low molecular weight diol in an amount less than 1.0 times the molar amount of the second polymeric diol. In addition, the prepolymer having the isocyanate terminal can also be obtained by reacting the second diisocyanate in an amount of 2 times or more the molar amount of the second polymeric diol in two steps, dividing it into two steps, one part in an amount of 1.3 to 2.5 times, particularly preferably 1.8 to 2.1 times the molar amount of the polymeric diol and the remaining part. More specifically, it can be obtained by a reaction process in the form of steps, in which the second polymeric diol in an amount of 90 to 40% based on the total amount of the first and second polymeric diols are first reacted with the second diisocyanate in an amount of 1.3 to 2.5 times, particularly preferably 1.8 to 2.1 times the molar amount of the polymeric diol to give a third precursor and this third precursor is reacted with the second low molecular weight diol in an amount less than 1.0 times the molar amount of the second polymeric diol to give a fourth precursor. This fourth precursor is then reacted with the residual amount of the second diisocyanate to give the prepolymer having the isocyanate terminal. In the case that the prepolymer having the hydroxyl terminal is to be obtained by a process in the form of passages, when the amount of the first diisocyanate used in the reaction of the first stage of the prepolymer having the hydroxyl terminal is greater than 2.5 Sometimes the molar amount of the first polymeric diol is likely to have an abnormal reaction product such as molecules of D (ID) m (m >); 2) in the prepolymer having the hydroxyl terminal in large amounts, (D means a low molecular weight and I means diisocyanate in the abbreviation, the same will apply later). If the amount of the first diisocyanate is less than 1.3 times that of the first polymeric diol, a large amount of diisocyanate monomer is contained and remains in the polymer having the isocyanate terminal, so it is likely that a reaction product forms such as molecules of I (DI) n (n> 2 =) during a reaction between the prepolymer having "a hydroxyl terminal and the prepolymer having an isocyanate terminal, that is, when the amount of the first diisocyanate is greater than 2.5 times the molar amount of the first polymeric diol and less than 1.3 times the molar amount of the first polymeric diol, does not exert a good influence on the spinning stability The hydroxyl terminal prepolymer production conditions such as the temperature of The reaction and the reaction time can be controlled according to the types of starting material components, for example, when the first polymeric diol, the first diisocyanate and the first low molecular weight diol are reacted by a one-pass process, the reaction temperature is preferably from 60 to 130 ° C, particularly preferably from 80 to 120 ° C, and the reaction time is preferably 30 to 100 minutes, particularly preferably 50 to 70 minutes. When they are reacted by a process in steps, the reaction temperature of a reaction between the first polymeric diol and the first diisocyanate is preferably 60 to 130 ° C, particularly preferably 80 to 120 ° C and the reaction time is preferably 30 to 100 minutes, particularly preferably 50 to 70 minutes. The reaction temperature of a reaction between the first precursor obtained and the low molecular weight diol is preferably 60 to 130 ° C, particularly preferably 80 to 100 ° C. In the case of the prepolymer having the isocyanate terminal, for example, the second polymeric diol can be reacted with the second diisocyanate in an amount 2 times or more the molar amount of the second polymeric diol to give the second precursor. When the amount of the second low molecular weight diol to be reacted with this precursor is small, specifically less than 1.0 times the molar amount of the second polymeric diol, an abnormal reaction product as described above is hardly formed, which does not cause problems . The production conditions of the prepolymer having the isocyanate terminal such as reaction temperature and reaction time can be controlled according to the types of the components of the starting material. For example, when the second polymeric diol, the second diisocyanate and the second low molecular weight diol are reacted by a one-pass process, the reaction temperature is preferably from 60 to 130 ° C, particularly preferably from 80 to 120 °. C and the reaction time of preference is 30 to 100 minutes, particularly preferably 50 to 70 minutes. When they are reacted by a process in the form of steps, the reaction temperature of a reaction between the second polymeric diol and the second diisocyanate is preferably from 60 to 130 ° C, particularly preferably from 80 to 120 ° C, and the time of reaction preferably from 30 to 100 minutes, particularly preferably from 50 to 70 minutes. When the low molecular weight diol is reacted with the obtained second precursor, the reaction temperature of a reaction between the obtained second precursor and the low molecular weight diol is preferably 60 to 130 ° C, particularly preferably 80 at 100 ° C. Stirring conditions or the like can also be determined adequately. The viscosity of the prepolymer having the hydroxyl terminal and the prepolymer having the isocyanate terminal differ according to the types and the mixing ratio of the starting materials used, reaction temperature and the like. The types and mixing ratio of the starting materials used are determined by the properties of a polyurethane elastic material for construction purposes, however, in the present invention, the molecular weight ratio of each constituent component is adjusted so that the viscosity of the two different prepolymers should be relatively close to one another. The viscosity ratio of the two different prepolymers preferably is 10 times or less, more preferably 5 times or less, particularly preferably 4 times or less, and should almost be applied to the volume ratio. The two different prepolymers described above are supplied in a reactor having a unit for delivering a reaction product to an outlet in a fixed ratio while mixing and stirring continuously during a fixed reaction time to form a polyurethane polymer and the The obtained polyurethane polymer is continuously extruded from a nozzle while taking the form of fluid, cooled and rewound to give a polyurethane elastic material. Elastic materials having various shapes similar to fiber, tape, color, tube and the like, can be obtained according to the shape of the nozzle. The production process of the present invention is particularly effective when a fiber, i.e., a polyurethane elastic yarn, is produced. Preferred examples of the polymeric diol having a molecular weight of 600 or more used in the production process of the present invention include, for example, condensates of dihydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, hexanediol, neopentyl glycol, 3-methyl- l, 5-pentanediol and dicarboxylates such as adipic acid and sebacic acid; polyester glycols such as polycaprolactone; and polyether glycols obtained by ring opening polymerization of ethylene oxide, tetrahydrofuran of propylene oxide and the like. These polymeric diols can be used alone or mixed with two or more. When the molecular weight of the polymeric diol is less than 600, the elongation of the elastic material obtained is very low, which is not preferred. On the contrary, when the molecular weight of the polymeric diol is very high, the elastic recovery deteriorates. However, because this is largely involved with other factors, it is difficult to determine what is the preferred upper limit. Generally speaking, the preferred molecular weight scale, which differs according to the types and amounts of the low molecular weight diol and the diisocyanate, in most cases is from 600 to 3,000.

The type of polymeric diol can be appropriately selected according to the required physical properties that differ according to the purpose of application. For example, when the first polymeric diol and the second polymeric diol are polyester diols, the obtained polyurethane elastic material or elastic yarn is excellent in abrasion resistance, oil resistance, tear resistance and the like. When the first polymeric diol and the second polymeric diol are polyether diols, the elastic material or polyurethane elastic yarn obtained is excellent in resistance to hydrolysis, resistance to fungi and the like. In addition, a polyester diol and a polyether diol can be used in combination to obtain the advantages of both the polyester diol and the polyether diol. When a polyester diol and a polyether diol are used in combination, both can be mixed and used to produce a prepolymer having a hydroxyl terminal and a prepolymer having an isocyanate terminal. In order to effectively develop the physical properties of both materials, it is preferred that a polyether diol be used as the first polymeric diol constituting the hydroxyl terminal prepolymer and a polyester diol could be used as the second polymeric diol constituting the prepolymer having the isocyanate terminal. That is, it is observed that the use of a larger amount of the polyester diol becomes more effective in improving the abrasion resistance, oil resistance, tear resistance and the like, of the polyurethane elastic material, and the like, while the mixed binder of the polyester diol of an amount of 15 mol% or more based on the total amount of the polymeric diols becomes effective to improve the resistance to the fungus of the elastic polyurethane material or the like. Therefore, to effectively develop the physical properties of both materials, it is recommended to mix the polyester diol in an amount greater than the polyether diol such that the polyether diol is used in an amount of 15 to 50 mol%, preferably from 15 to 35 mol% and the polyester diol should be used in an amount of 85 to 50 mol%, preferably 85 to 65 mol%, based on the total amount of the polymeric diols. As for the mixing of the polymeric diols in the prepolymer having the hydroxyl terminal and the prepolymer having the isocyanate terminal, in order to reduce a difference in viscosity between both prepolymers, a larger amount of a polymeric diol is preferably mixed in the prepolymer having the isocyanate terminal. To satisfy these, it is preferred that a polyether diol should be used as the first polymeric diol constituting the prepolymer having the hydroxyl terminal and a polyester diol should be used as the second polymeric diol constituting the prepolymer having the terminal of isocyanate. Preferred examples of the low molecular weight diol having a molecular weight of 500 or less used in the production process of the present invention include ethylene glycol, propylene glycol, butylene glycol, hexanediol, bis-β-hydroxyethoxybenzene, cyclohexane dimethanol and the like, which butylene glycol is the particularly preferred. Preferred examples of this diisocyanate include tolylene diisocyanate, diphenylmethane diisocyanate, hydrides thereof, isophorone diisocyanate, hexamethylene diisocyanate and the like, of which diphenylmethane diisocyanate is particularly preferred. The above low molecular weight diols having a molecular weight of 500 or less, and the above diisocyanates can be used alone or by mixing two or more. In the production process of the present invention, the optional components such as titanium oxide, ultraviolet absorbent and antioxidant which are generally used in the production of a polyurethane elastic material and the like, they can be mixed in the starting materials. In the production process of the present invention, polyurethane polymers are obtained in the liquid state, by mixing, stirring and continuously reacting the prepolymer having the hydroxyl terminal with the prepolymer having the isocyanate terminal and extruded from a nozzle continuously to give an elastic polyurethane or yarn material. That is, it can be such that the production process of the present invention is a kind of reaction spinning process. A reactor for carrying out a reaction between the prepolymer having a hydroxyl terminal and the prepolymer having the isocyanate terminal can be a commonly used reactor and is not particularly limited if it has the structure that does not have a short path for its content between an inlet for the two different previous prepolymers and an outlet for a polyurethane polymer having a unit for delivering the two different prepolymers to the outlet by continuously mixing and stirring them maintaining a predetermined reaction time. To mix and stir in the reactor, rotating agitators such as screw-type and stirring-type agitators and static mixing agitators can be used. Although such conditions as the reaction time and reaction temperature of a reaction of the prepolymer having the hydroxyl terminal and the prepolymer having the isocyanate terminal in the reactor can be controlled according to the types of starting materials, etc. , the reaction time is preferably from 1 to 90 minutes, particularly preferably from 1 to 60 minutes and the reaction temperature is preferably from 160 to 220 ° C, particularly preferred from 180 to 210 ° C. The function of the present invention will be described in detail later. Since D (ID) m (m >; 2), I (DI) n (n> 2) and the like, which are the reaction products of the low molecular weight diol and the diisocyanate, generally have a high melting point and poor solubility in a prepolymer and deteriorate the Yarn stability, it is necessary to eliminate the formation of the above compounds. On the other hand, a repetition of -IDID- is indispensable as a hard segment for the structure of elastic polyurethane material or the like from the point of view of thermal properties and elasticity. In the present invention, for example, from 1.3 to 2.5 moles of the first diisocyanate based on 1 mole of the first polymeric diol (which will be abbreviated as P hereinafter) and an excessive molar amount of the first low molecular weight diol are reacted one with the other to form a prepolymer having a hydroxyl terminal in the mixed state of DIPID and D as much as possible, while a prepolymer has the isocyanate terminal in a mixed state of IPI and I is formed by reacting the second polymeric diol with the second diisocyanate directly or this reaction product is further reacted with the second low molecular weight. When the two different prepolymers are reacted with one another in a reactor, the first diol of low molecular weight contained in the prepolymer having the hydroxyl terminal and the second diisocyanate monomer contained in the prepolymer having the isocyanate terminal first they are preferably reacted with one another to form a hard segment having a repeated structure of -IDID- between DIPID and IPI in a well-balanced form, while the elastic polyurethane material or the elastic yarn obtained by the production process of the present invention achieves superior thermal performance than that of the elastic polyurethane material or elastic yarn obtained by the one-pass process or the conventional pre-polymer process. In addition, part of the low molecular weight diol was already consumed at the time of the synthesis of the prepolymer having a hydroxyl terminal, part of the diisocyanate was also consumed in a reaction with the polymeric diol, part of the diisocyanate was already consumed and part of the diol low molecular weight (not contained from the beginning) at the time of synthesizing the prepolymer having the isocyanate terminal so that the formation of an abnormal reaction product such as D (ID) m (m > 2), I ( DI) n (n> 2) is largely eliminated in spin stability is improved compared to the one-pass process or the conventional polymer process. The viscosity of a low molecular weight diol having a molecular weight of 500 or less is several tens of cP in the molten state and the viscosity of a diisocyanate is extremely low at 10 cP or lower in the molten state. In contrast to this, the viscosity of a polymeric diol is several hundred cP in the molten state, which is much higher than the low molecular weight diols and the diisocyanates. In the conventional reaction spinning process of the elastic polyurethane material or the like, especially elastic yarn, each of the starting materials to be reacted which differ greatly in viscosity and have a volume ratio of 10 times or more one with the other are used directly and mixed in a very short period with the result that an abnormal reaction product caused by non-uniform mixing is easily formed and therefore lacks stability and spinning. In the present invention, the viscosity of the prepolymer having the hydroxyl terminal can be adjusted to almost a range of 500 to 10,000 cP at 70 ° C and the viscosity of the prepolymer having an isocyanate terminal at almost a scale of 800 to 5,000 cP controlling the mixing ratio of the polymeric diol in the two different prepolymers used, for example, to the scale described above, making it possible to improve the stability of the yarn. To also improve this effect, the reaction process in the form of previous steps is preferably employed to synthesize the prepolymer having the hydroxyl terminal. That is, the first polymeric diol is reacted with the second diisocyanate in an amount of 1.3 to 2.5 times, preferably 1.8 to 2.1 times the molar amount of the first polymeric diol to form an IPI which is formed by reacting a polymeric diol with diisocyanate at both ends of a polymeric diol as much as possible, which is then reacted with an excessive molar amount of the low molecular weight diol to form a prepolymer having the hydroxyl terminal in the mixed state of DIPID, and D, thus suppressing the formation of an abnormal reaction product, and further improving the stability of the yarn. In the synthesis of the prepolymer having the isocyanate terminal, the low molecular weight diol is preferably used in the amount of less than 1.0 times the molar amount of the polymeric diol from the point of view of spin stability. Also in this case, a reaction in the form of steps is preferably carried out. In other words, IPI is formed, which is reacted with the low molecular weight diol, it forms a prepolymer having an isocyanate terminal comprising IPIDIPI as the main component, thus making possible the suppression of the formation of a product of abnormal reaction In addition, even when a polyester diol and a polyether diol having low compatibility with one another, the polymeric diols, are to be mixed, a prepolymer having an isocyanate terminal and a prepolymer having a terminal and hydroxyl is independently formed. , as an advance to achieve an excellent mixed state of both the prepolymers and the production process of the present invention with the result that a polyurethane elastic material having the advantages of both polymeric diols can be obtained. The following examples are given to further illustrate the present invention. Example 1 Twenty-four parts by weight of diphenylmethane diisocyanate and 22 parts by weight of butylene glycol were reacted continuously with 100 parts by weight of the polyethylene adipate to obtain hydroxyl groups on both terminals (molecular weight 2,100) with stirring at a reaction temperature of 115 ° C for a reaction time of 60 minutes to give a prepolymer having the hydroxyl terminal. This prepolymer having the hydroxyl terminal had a viscosity of 4,000 cP at 70 ° C. While, 84 parts of the diphenylmethane isocyanate were continuously reacted with 200 parts by weight of polyethylene adipate having hydroxyl groups at both terminals (molecular weight of 2,100) with stirring at a reaction temperature of 115 ° C for one hour. reaction time of 60 minutes to give a prepolymer having the isocyanate terminal. This prepolymer having the isocyanate terminal has a viscosity of 1,500 cP at 70 ° C. One hundred and forty-six parts by weight of the prepolymer thus obtained having the hydroxyl terminal and 284 parts by weight of the prepolymer obtained having the isocyanate terminal were continuously injected into a heat exchange reactor with scraped surface and mixed and stirred at a temperature of 190 ° C during a residence time of 30 minutes. The obtained viscous product was immediately extruded from a nozzle by a spin pump and treated with a lubricant composed mainly of mineral oil and then the winding operation of 40 denier polyurethane elastic yarn at a rate of 500 m / minute was carried performed continuously for 7 days. The molar ratio of the total molar amount of the diols (polyethylene adipate and butylene glycol) to the diisocyanate (diphenylmethane diisocyanate) were both used as the starting materials of the obtained polyurethane elastic yarn was 1 to 1.12. In the case of the production process of the present invention, yarn breakage occurred during spinning twice, which was less than half the number of yarn break times when spinning was carried out directly by the conventional pass process or the prepolymer process. The elongation of the polyurethane elastic yarn obtained is 450% which is equal to that obtained by conventional processes. When the residual residual permanent fixation was measured after 1 minute of treatment at 115 ° C in 100% elongation, for 30%, which was 45% lower than that obtained by conventional processes. By comparing the viscosity ratio and the volume ratio of each of the constituent components such as the starting materials or prepolymers when the above starting materials were used to carry out the process of the present invention and the conventional processes, this was show later. <; conventional process: a one-step process > constituent components ratio of viscosity ratio volume polymeric diol 110 12 low molecular weight diol 10 1 diisocyanate 1 4 < conventional process: prepolymer process > constituent components ratio of viscosity ratio prepolymer volume having 43 16 isocyanate diol terminal of low molecular weight < Example 1 > constituent components ratio of viscosity ratio volume prepolymer having 1.8 terminal hydroxyl prepolymer having isocyanate terminal Physical properties are measured according to the following methods. The same should apply the following examples. (Viscosity) The sample was heated to 70 ° C for about 3 hours and the viscosity of the sample was measured using the type B viscometer from Tokyo Keiko Co. , Ltd. (elongation (%): in the case of yarn) A load of 0.1 g is given to the sample at an ambient temperature of 20 ° C and a humidity of 65% to prepare a sample in an initial state with a length grip of 4 cm. This sample in the initial state was lengthened at the rate of 30 cm / minute until it breaks and the length "A" is obtained by subtracting the length of grip from the length of the sample at the time of rupture to calculate the elongation of the equation 1 below. Ten samples were measured for each type and the average measurement values were taken as the elongation of the sample. equation 1: elongation (%) = A / 40 x 100 (elongation (%): in the case of tape) The elongation (%) of a tape was measured according to the JIS standards (K 7311). (Permanent Residual Batch Fixation (%)) A load of 0.1 g is given to the sample at an ambient temperature of 20 ° C and a humidity of 65% to prepare a sample in an initial state with a grip length of 4 cm . The lengthening operation of this sample in the initial __status to a length of 16 cm and the loosening of it to 4 cm was repeated twice. The tension was measured during this operation, the tension and the elongation length were expressed in a graph, the elongation length "B" of the sample was calculated when the tension became null by loosening the sample for the second time, and the fixation Permanent residual residual (%) is obtained from equation 2 below. Five samples were measured for each type and the average measurement values were taken as the residual permanent residual fixation of the sample. Equation 2: permanent residual residual fixation (%) = B / 40 x 100 (resistance to fungi) The covering yarn is produced from the wool sample and nylon (WN50 / 16/1) and woven in a cylinder with a 360-turn weaving machine. This woven cylinder is cut horizontally at every 7 cm in width as samples. An appropriate amount of water is added to soil that is placed through a sieve and mixed lightly, and the sample is buried, covered and left at 24 to 26 ° C. After a predetermined time, the sample is removed and the pores (the existence of pores, the day number, the number of pores, etc.) formed in the sample and the like, are reviewed. EXAMPLES 2 Twenty-four parts by weight of diphenylmethane diisocyanate were reacted with 100 parts by weight of polyethylene adipate having hydroxyl groups on both terminals (molecular weight of 2,100) at a reaction temperature of 80 ° C for a reaction time of 60 minutes. minutes to give a precursor. One hundred twenty-four parts by weight of the obtained precursor was then reacted continuously with 33 parts by weight of butylene glycol with stirring at a reaction temperature of 115 ° C for a reaction time of 60 minutes to give a prepolymer having a hydroxyl terminal. The prepolymer has a hydroxyl terminal had a viscosity of 5,000 cP at 70 ° C. Meanwhile, 110 parts by weight of diphenylmethane diisocyanate was reacted with 200 parts by weight of polyethylene adipate having hydroxyl groups on both terminals (molecular weight of 2,100) continuously with stirring at a reaction temperature of 80 ° C for one hour. reaction time of 60 minutes to give a prepolymer having an isocyanate terminal. This prepolymer having the isocyanate terminal had a viscosity of 1,500 cP at 70 ° C. One hundred fifty-seven parts by weight of the prepolymer thus obtained having the hydroxyl terminal and 310 parts by weight of the prepolymer obtained having the isocyanate terminal were continuously injected into a heat exchange reactor with scraped surface and mixed and stirred at a temperature reaction temperature of 190 ° C for a residence time of 30 minutes. The obtained viscous product was immediately extruded from a nozzle by a spin pump and treated with a lubricant composed mainly of mineral oil and then wound to produce 70 denier polyurethane elastic yarn. When the winding operation at a rate of 350 m / minute was carried out continuously for 7 days, the clogging of the nozzle was not observed at all. When the reactor was disassembled to inspect the inner part of the reactor after the previous experiment was repeated three times at 7 days, the adhesion of the abnormal reaction product was not observed. The molar ratio of the total molar amount of the diols (polyethylene adipate and butylene glycol) to the diisocyanate (diphenylmethane diisocyanate) were both used as the starting materials of the polyurethane elastic yarn obtained was from 1 to 1.05. The elongation of the polyurethane elastic yarn obtained was 500%. When the permanent residual starting fixation after 1 minute of treatment at 115 ° C at an elongation of 100% was measured at a thermal performance index, it was 35%. Example 3 Twenty-four parts by weight of diphenylmethane diisocyanate and 28 parts by weight of butylene glycol were reacted with 100 parts by weight of polyethylene adipate having hydroxyl groups on both terminals (molecular weight of 2,100) continuously with stirring at a reaction temperature of 115 ° C for a reaction time of 60 minutes to give a prepolymer having a hydroxyl terminal. This prepolymer has a hydroxyl terminal had a viscosity of 4,500 cP at 70 ° C. Meanwhile, 96 parts by weight of diphenylmethane diisocyanate were reacted with 200 parts by weight of polyethylene adipate having hydroxyl groups on both terminals (molecular weight 2)., 100) continuously with stirring at a reaction temperature of 115 ° C for a reaction time of 60 minutes to give a prepolymer having isocyanate terminal. This prepolymer having the isocyanate terminal had a viscosity of 1,800 cP at 70 ° C. One hundred fifty-two parts by weight of the prepolymer thus obtained having the hydroxyl terminal and 296 parts by weight of the prepolymer obtained having the isocyanate terminal were continuously injected into a screw extrusion molding machine, mixed and stirred at a temperature of reaction at 190 ° C for a residence time of 10 minutes. The obtained viscous product was immediately extruded from a slip nozzle by a spin pump and treated with a lubricant obtained by dispersing the fats in water with a surfactant and then the winding operation of a 10,000 denier polyurethane tape (width of approximately 6 mm and a thickness of approximately 180 μm) at the rate of 50 m / minute was carried out continuously for 7 days. The molar ratio of the total molar amount of the diols (polyethylene adipate and butylene glycol) and diisocyanate (diphenylmethanediisocyanate), both used as the starting materials of the obtained polyurethane tape, was from 1 to 1.06. In the case of the conventional method for the extrusion molding of polyurethane resin pellets, 2 or 3 points that were not uniform in width are generally produced based on 10,000 m, mainly resulting from the non-uniform melting of the pellets during molding. extrusion. In contrast, in the case of the process of the present invention, the non-uniform point in width was reduced to a point or less based on 100,000 m. The elongation of the polyurethane tape thus obtained was 400%, which is equal to that produced by the processes of the prior art. The elongation of the obtained polyurethane tape was measured as the thermal performance index of the tape when the tape was stretched and broke by placing a 3 mm diameter iball heated at 130 ° C on the tape. It was found that the elongation of the tape of the present invention was 150% when the elongation of a tape produced in the prior art process is 100%. When the permanent residual starting fixation after 1 minute of treatment at 115 ° C at an elongation of 100% was measured at 50%. Example 4 Twenty-four parts by weight of diphenylmethane diisocyanate were reacted with 100 parts by weight of polyethylene adipate at a reaction temperature of 115 ° C for a reaction time of 60 minutes to give a precursor. One hundred twenty-four parts by weight of the obtained precursor was then reacted with 28 parts by weight of butylene glycol continuously with stirring at a reaction temperature of 115 ° C for a reaction time of 60 minutes to give a prepolymer having a hydroxyl terminal. This prepolymer having the hydroxyl terminal had a viscosity of 4,500 cP at 70 ° C. Meanwhile, 96 parts by weight of diphenylmethane diisocyanate were reacted with 200 parts by weight of polyethylene adipate having "hydroxyl groups on both terminals (molecular weight of 2,100) continuously with stirring at a reaction temperature of 115 ° C during a reaction time of 60 minutes to give a prepolymer having isocyanate terminal This prepolymer having the isocyanate terminal had a viscosity of 1,800 cP at 70 ° C. One hundred fifty-two parts by weight of the prepolymer thus obtained having the terminal of hydroxyl and 296 parts by weight of the prepolymer obtained having the isocyanate terminal were injected continuously into a screw extrusion molding machine, mixed and stirred at a reaction temperature of 190 ° C for a residence time of 10 minutes. The obtained viscous product was immediately extruded from a slip nozzle by a spin pump and treated with a lubricant. The product obtained by the dispersion of fats in water with a surfactant and then the winding operation of a 10,000 denier polyurethane tape (width of approximately 6 mm and a thickness of approximately 180 μm) at the rate of 50 m / minute was performed continuously for 7 days. The molar ratio of the total molar amount of the diols (polyethylene adipate and butylene glycol) and the diisocyanate (diphenylmethane diisocyanate), both used as the starting materials of the obtained polyurethane tape, was 1.06 to 1. In the case of the conventional method for the extrusion molding of polyurethane resin pellets, 2 or 3 points which were not uniform in width are generally produced based on 10,000 m, mainly resulting from non-uniform melting of the pellets during extrusion molding. In contrast, in the case of the process of the present invention, the non-uniform point in aachura was reduced to a point or less based on 300,000 m. The elongation of the polyurethane tape obtained was 420% The elongation of the obtained polyurethane tape was measured as the thermal performance index of the tape when the tape was stretched and broke by placing a 3 mm diameter iron ball heated at 130 ° C on the tape. It was found that the elongation of the tape of the present invention was 160% when the elongation of the tape produced by prior art process was 100%. When the permanent residual starting fixation after 1 minute of treatment at 115 ° C at an elongation of 100% which was measured was 45%. Example 5 Seventy-five parts by weight of diphenylmethane diisocyanate were reacted with 100 parts by weight of polytetramethylene glycol having hydroxyl groups on both terminals (molecular weight 650) at a reaction temperature of 80 ° C for a reaction time of 60. minutes to give a precursor. One hundred seventy-five parts by weight of the obtained precursor were reacted with 58 parts by weight of butylene glycol continuously with stirring at a reaction temperature of 80 ° C for a reaction time of 60 minutes to give a prepolymer having a hydroxyl terminal. This prepolymer having the hydroxyl terminal had a viscosity of 5., 500 cP at 70 ° C. Meanwhile, 173 parts by weight of diphenylmethane diisocyanate were reacted with 327 parts by weight of polyethylene adipate having hydroxyl groups on both terminals (molecular weight of 2,100) continuously with stirring at a reaction temperature of 80 ° C for a time 60 minute reaction time to give a prepolymer having the isocyanate terminal. This prepolymer having the isocyanate terminal had a viscosity of 1,300 cP at 70 ° C. Two hundred and thirty-three parts by weight of the prepolymer obtained having the hydroxyl terminal and 500 parts by weight of the prepolymer obtained having the isocyanate terminal were continuously injected into a scraped surface heat exchange reactor, mixed and stirred at a temperature reaction temperature of 190 ° C for a residence time of 30 minutes. The obtained viscous product was immediately extruded from a nozzle by a spin pump, treated with a lubricant composed mainly of mineral oil and then wound to produce the 20 denier polyurethane elastic yarn. The polytetramethylene glycol was counted for 59 mole% of the total molar amount of the polytetramethylene glycol polymer diols and polyethylene adipate) used as the starting materials of the obtained polyurethane elastic yarn. The molar ratio of the total molar amount of the diols (polytetramethylene glycol, butylene glycol and polyethylene adipate) to the diisocyanate (diphenylmethane diisocyanate) was 1 to 1.10. When the winding operation at a rate of 800 m / minute was carried out continuously for 7 days, the clogging of the nozzle was not observed at all. The elongation of the polyurethane elastic yarn obtained was 440%. When the permanent residual starting fixation after 1 minute of treatment at 115 ° C at an elongation of 100% was measured as the thermal performance index, it was 35%. The measurement result of fungal resistance was good at 28 days. EXAMPLE 6 Forty-eight parts by weight of diphenylmethane diisocyanate was reacted with 100 parts of polytetramethylene glycol having hydroxyl groups on both terminals (molecular weight 1,000) at a reaction temperature of 80 ° C for a reaction time of 60 minutes for give a forerunner One hundred and forty-eight parts by weight of the obtained precursor were reacted with 54 parts by weight of butylene glycol continuously with stirring at a reaction temperature of 80 ° C for a reaction time of 60 minutes to give a prepolymer having a hydroxyl terminal. This prepolymer having the hydroxyl terminal had a viscosity of 5,000 cP at 70 ° C. While 190 parts by weight of diphenylmethane diisocyanate were reacted with 445 parts by weight of polyethylene propylene adipate having hydroxyl groups on both terminals (molecular weight of 2,100, EG: PG = 1: 9) continuously with stirring at a reaction temperature at 80 ° C for a reaction time of 60 minutes to give prepolymer having the isocyanate terminal. This prepolymer having the isocyanate terminal had a viscosity of 2,000 cP at 70 ° C. Two hundred and two parts by weight of the prepolymer thus obtained having the hydroxyl terminal and 708 parts by weight of the prepolymer obtained having the isocyanate terminal were continuously injected into a scraped surface heat exchange reactor, mixed and stirred at a temperature of 190 ° C reaction for a residence time of 30 minutes. The viscous product obtained was immediately extruded into a nozzle by a spin pump, treated with a lubricant mainly composed of mineral oil and then wound to produce the 20 denier polyurethane elastic. Polytetramethylene glycol accounted for 32 mol% of the total amount of the polymeric diols (polytetramethylene glycol and polyethylene propylene adipate). The molar ratio of the total molar amount of the diols (polytetramethylene glycol), butylene glycol and polyethylene propylene adipate) to the diisocyanate (diphenylmethane diisocyanate) was from 1 to 1.05. When the winding operation was carried out at a rate of 800 m / minute continuously for 7 days, the clogging of the nozzle was not observed at all. The elongation of the polyurethane elastic yarn obtained was 490%. The permanent residual residual fixation after 1 minute of treatment at 115 ° C is an elongation of 100% was 30% as the thermal performance index. The measurement result of the fungal resistance was good at 19 days. (By reference, the result of measuring the resistance to the fungus when the polymer diols produced by the prepolymer process in Comparative Example 2 were 3-day polyester diols). Example 7 Twenty-four parts by weight of diphenylmethane diisocyanate were reacted with 100 parts by weight of polytetramethylene glycol having hydroxyl groups on both terminals (molecular weight 2,000) at a reaction temperature of 80 ° C for a reaction time of 60 minutes to give a forerunner One hundred twenty-four parts by weight of the obtained precursor was reacted with 60 parts by weight of butylene glycol continuously with stirring at a reaction temperature of 80 ° C for a reaction time of 60 minutes to give a prepolymer having the hydroxyl terminal. This hydroxyl group-terminated prepolymer had a viscosity of 3,500 cP at 70 ° C. Meanwhile, 240 parts by weight of diphenylmethane diisocyanate was reacted with 500 parts by weight of polyethylene propylene adipate having hydroxyl groups on both terminals (molecular weight of 2,100, EG: PG = 1: 9) continuously with stirring at a temperature of reaction of 80 ° C for a reaction time of 60 minutes to give a prepolymer having an isocyanate terminal. This prepolymer having isocyanate terminal had a viscosity of 1,800 cP at 70 ° C. One hundred and eighty-four parts by weight of this obtained prepolymer having the hydroxyl terminal and 750 parts by weight of the obtained prepolymer having isocyanate terminal were continuously injected into a surface reactor exchange reactor, mixed and stirred at a temperature of 190 ° C reaction for a residence time of 30 minutes. The obtained viscous product was immediately extruded from a nozzle by a pump, treated with a lubricant composed mainly of mineral oil and then wound to produce 20 denier polyurethane elastic yarn. The polytetramethylene glycol accounted for 17 mol% of the total amount of the polymeric diols (polytetramethylene glycol and polyethylene propylene adipate). The molar ratio of the total molar amount of the diols (polytetramethylene glycol, butylene glycol and polyethylene propylene adipate) to the diisocyanate (diphenylmethane diisocyanate) was 1 to 1.12. When the winding operation at a rate of 800 m / minute was carried out continuously for 7 days, the clogging of the nozzle was not observed at all. When the reactor was disassembled to inspect the inside of the reactor after 7 days of continuous operation it was repeated three times, the reaction of an abnormal reaction product was observed. The elongation of the polyurethane elastic yarn obtained was 420%. The permanent residual starting fixation after 1 minute of treatment at 115 ° C at an elongation of 100% was 31% as the start of thermal performance. The result of the resistance reaction to the fungus was good at 18 days. Comparative Example 1 The spinning was carried out according to the process of a heavy one using 100 parts by weight of polyethylene adipate (molecular weight of 2,100), 40 parts by weight of diphenylmethane diisocyanate and 8 parts by weight of butylene glycol. When the winding operation at a rate of 800 m / min, the clogging of the nozzle occurred in one day. When the reactor is disassembled after continuous spinning, a large amount of an abnormal reaction product adhered in the inner part of the reactor. The residual residual permanent fixation after 1 minute of treatment at 115 ° C in the 100% elongation was 50% which is worse than the polyurethane elastic yarn obtained by the production process of the present invention. Comparative Example 2 The winding was carried out according to the conventional prepolymer process by reacting 100 parts by weight of polyethylene adipate (molecular weight of 2,100) with 40 parts by weight of diphenylmethane diisocyanate to give a prepolymer and then reacting the prepolymer obtained with 8 parts by weight of the butylene glycol. When the winding operation at a rate of 800 m / min was carried out, the clogging of a nozzle occurred in two days. The adhesion of an abnormal adhesion product was observed in the internal part of the reactor as Comparative Example 1. The permanent residual starting fixation after 1 minute of treatment at 115 ° C in an elongation of 100% was 50% which is worse than the elastic polyurethane yarn obtained by the production process of the present invention.

Industrial Applicability In the present invention, a polymerization reaction was carried out after a prepolymer having an isocyanate terminal and a prepolymer having a hydroxyl terminal was obtained, wherein the viscosity of the two is relatively close and the The volume ratio of the two is almost 1 compared to that of the conventional process, thus making it possible to uniformly mix the reactants and suppress the formation of abnormal reaction products with the result that the spin stability can be greatly improved. Furthermore, the formation of the abnormal reaction products is suppressed by using the prepolymers in two steps and a stirring effect was improved by controlling the viscosity of the two prepolymers at the same level, thus making it possible to further improve the stability of the yarn. In addition, the mixing ratio of the starting materials of the two different prepolymers in the present invention is excellent from the point of view of compatibility and can improve said quality in terms of thermal performance and resistance to fungi as well as spinning stability.

Claims

CLAIMS 1. A process for producing polyurethane elastic yarn of a first polymeric diol having a molecular weight of 600 or more, a second polymeric diol which can be the same or different from the first polymeric diol and has a molecular weight of 600 or more, a first low molecular weight diol having a molecular weight of 500 or less, a second low molecular weight diol which may be the same or different from the first low molecular weight diol, a first diisocyanate and a second diisocyanate which may be the same or different from the first diisocyanate as main starting materials, the total amount of the first diisocyanate and the second diisocyanate in the starting materials being 0.95 to 1.25 times the total molar amount of the first polymeric diol, second polymeric diol, the first molecular weight diol low and the second low molecular weight diol, characterized in that it comprises the step of: continuously extruding from a nozzle a polyurethane polymer liquid state obtained by continuously reacting a prepolymer having a hydroxyl terminal obtained by reacting the first polymeric diol, the first low molecular weight diol and the first diisocyanate, with a prepolymer having a diisocyanate terminal obtained by reacting the second polymeric diol, the second diol of low molecular weight and the second diisocyanate.
2. The process for producing polyurethane elastic yarn according to claim 1, characterized in that the amount of the second low molecular weight diol is less than 1.0 times the molar amount of the second polymeric diol.
3. The process for producing polyurethane elastic yarn according to claim 1 or 2, characterized in that the prepolymer having the hydroxyl terminal is obtained by reacting the first polymeric diol in an amount of 60 to 10 mol% based on the total amount of the first polymeric diol and the second polymeric diol, the first diisocyanate in an amount of 1.3 to 2.5 times the amount of the first polymeric diol and the first low molecular weight diol in an amount of 2 times or more the molar amount of the first polymer diol and the prepolymer having isocyanate terminals, is obtained by reacting the second polymeric diol in an amount of 90 to 40 mol% based on the total amount of the first polymeric diol and the second polymeric diol, the second diisocyanate in an amount 2 times or more the molar amount of the second polymeric diol and the second low molecular weight diol in an amount less than 1.0 times the molar amount of the second polymeric diol. . The process for producing polyurethane elastic yarn according to claim 1 to 3, characterized in that the prepolymer having the hydroxyl terminal is obtained by reacting the first polymeric diol and the first diisocyanate to give a first precursor and then reacting the first precursor and the first low molecular weight diol, and the prepolymer having the isocyanate terminal is obtained by reacting the second polymeric diol and the second diisocyanate to give a second precursor and then reacting the second precursor and the second low molecular weight diol in an amount less than 1.0 times the molar amount of the second polymeric diol. The process for producing polyurethane elastic yarn according to claim 1 to 4, characterized in that the first polymeric diol and the second polymeric diol are each selected from the group consisting of polyether diols and polyester diols. 6. The process for producing polyurethane elastic yarn according to claim 5, characterized in that the first polymeric diol is a polyether diol and the second polymeric diol is a polyester diol. 7. A process for producing an elastic polyurethane material from a first polymeric diol having a molecular weight of 600 or more, a second polymeric diol which can be the same or different from the first polymeric diol and has a molecular weight of 600 or more, a first low molecular weight diol having a molecular weight of 500 or less, a second low molecular weight diol which can being equal to or different from the first low molecular weight diol, a first diisocyanate and a second diisocyanate which may be the same or different from the first diisocyanate as the main starting materials, the total amount of the first diisocyanate and the second diisocyanate in the starting materials being from 0.95 to 1.25 times the total molar amount of the first polymeric diol, the second polymeric diol, the first low molecular weight diol and the second low molecular weight diol, and the amount of the second low molecular weight diol being less than 1.0 times the molar amount of the second polymeric diol, characterized in that it comprises the step of: continuously extruding from a nozzle a polyurethane polymer in Liquid obtained by continuously reacting a prepolymer having the hydroxyl terminal obtained by reacting the first polymeric diol, the first low molecular weight diol and the first diisocyanate, with a prepolymer having the diisocyanate terminal obtained by reacting the second polymeric diol, the second diol of low molecular weight and the second diisocyanate. 8. The process for producing a polyurethane elastic material according to claim 7, characterized in that the prepolymer having the hydroxyl terminal is obtained by reacting the first polymeric diol in an amount of 60 to 10 mol% based on the total amount of the first diol polymeric and the second polymeric diol, the first diisocyanate in an amount of 1.3 to 2.5 times the molar amount of the first polymeric diol and the first low molecular weight diol in an amount of 2 times or more the molar amount of the first polymeric diol and the Prepolymer having the isocyanate terminal is obtained by reacting the second polymeric diol in an amount of 90 to 40 mol% based on the total amount of the first polymeric diol and the second polymeric diol, the second diisocyanate in an amount of 2 times or more molar amount of the second polymeric diol and the second low molecular weight diol in an amount less than 1.0 times the amount molar of the second polymeric diol. The process for producing a polyurethane elastic material according to claim 7 or 8, characterized in that the prepolymer having the hydroxyl terminal is obtained by reacting the first polymeric diol and the first diisocyanate to give a first precursor and then reacting the first precursor and the first low molecular weight diol, and the prepolymer having the isocyanate terminal is obtained by reacting the second polymeric diol and the second diisocyanate to give a second precursor and then reacting the second precursor and the second weight diol low molecular weight in an amount less than 1.0 times the molar amount of the second polymeric diol. The process for producing a polyurethane elastic material according to any of claims 7 to 9, characterized in that the first polymeric diol and the second polymeric diol are each selected from the group consisting of polyether diols and polyester diols. 11. The process for producing a polyurethane elastic material according to claim 10, characterized in that the first polymeric diol is a polyether diol and the second polymeric diol is a polyester diol. 12. A process for producing polyurethane elastic yarn from a first polymeric diol having a molecular weight of 600 or more, a second polymeric diol which can be the same or different from the first polymeric diol and has a molecular weight of 600 or more, a first low molecular weight diol having a molecular weight of 500 or less, a first diisocyanate and a second diisocyanate which may be the same or different from the first diisocyanate as the main starting materials, the total amount of the first diisocyanate and the second diisocyanate in the materials starting from 0.95 to 1.25 times the total molar amount of the first polymeric diol, second polymeric diol, the low molecular weight diol characterized in that it comprises the step of: continuously extruding from a nozzle a polyurethane polymer in the liquid state obtained by continuously reacting a prepolymer having a hydroxyl terminal obtained by reacting the first polymer diol co, the low molecular weight diol and the first diisocyanate, with a prepolymer having the diisocyanate terminal obtained by reacting the second polymeric diol, the second diisocyanate. The process for producing polyurethane elastic yarn according to claim 12, further characterized in that the prepolymer having the hydroxyl terminal is obtained by reacting the first polymeric diol in an amount of 60 to 10 mol% based on the amount total of the first polymeric diol and the second polymeric diol, the first diisocyanate in an amount of 1.3 to 2.5 times the amount of the first polymeric diol and the low molecular weight diol in an amount of 2 times or more the molar amount of the first polymeric diol and the prepolymer having the isocyanate terminal is obtained by reacting the second polymeric diol in an amount of 90 to 40 mol% based on the total amount of the first polymeric diol and the second polymeric diol, and the second diisocyanate in an amount 2 times or more the molar amount of the second polymeric diol. The process for producing polyurethane elastic yarn according to claim 12 or 13, characterized in that the prepolymer having the hydroxyl terminal is obtained by reacting the first polymeric diol and the first diisocyanate to give a precursor and then reacting the precursor and the low molecular weight diol. 15. The process for producing polyurethane elastic yarn according to any of claims 12 to 14, characterized in that the first polymeric diol and the second polymeric diol each is selected from the group consisting of polyether diols and polyester diols. 16. The process for producing polyurethane elastic yarn according to claim 15, characterized in that the first polymeric diol is a polyether diol and the second polymeric diol is a polyester diol. 17. A process for producing a polyurethane elastic material of a first polymeric diol having a molecular weight of 600 or more, a second polymeric diol which can be the same or different from the first polymeric diol and has a molecular weight of 600 or more, a diol of low molecular weight having a molecular weight of 500 or less, a first diisocyanate and a second diisocyanate which may be the same or different from the first diisocyanate as starting materials, the total amount of the first diisocyanate and the second diisocyanate in the materials of starting from 0.95 to 1.25 times the total molar amount of the first polymeric diol, the second polymeric diol and the low molecular weight diol, characterized in that it comprises the step of: continuously extruding from a nozzle a polyurethane polymer in the obtained liquid state by reacting continuously a prepolymer having the hydroxyl terminal obtained by reacting the first polymeric diol, the diol of low molecular weight and the first diisocyanate, with a prepolymer having the diisocyanate terminal obtained by reacting the second polymeric diol and the second diisocyanate. 18. The process for producing a polyurethane elastic material according to claim 17, characterized in that the prepolymer having the hydroxyl terminal is obtained by reacting the first polymeric diol in an amount of 60 to 10 mol% based on the total amount of the first polymeric diol and the second polymeric diol, the first diisocyanate in an amount of 1.3 to 2.5 times the molar amount of the first polymeric diol and the low molecular weight diol in an amount of 2 times or more the molar amount of the first polymeric diol and the prepolymer having the isocyanate terminal is obtained by reacting the second polymeric diol in an amount of 90 to 40 mol% based on the total amount of the first polymeric diol and the second polymeric diol and the second diisocyanate in an amount 2 times or plus the molar amount of the second polymeric diol. 19. The process for producing a polyurethane elastic material according to claim 17 or 18, characterized in that the prepolymer having the hydroxyl terminal is obtained by reacting the first polymeric diol and the first diisocyanate to give a precursor and then reacting the precursor and the low molecular weight diol. 20. The process for producing a polyurethane elastic material according to any of claims 17 to 19, characterized in that the first polymeric diol and the second polymeric diol are each selected from the group consisting of polyether diols and polyester diols. 21. The process for producing a polyurethane elastic material according to claim 20, characterized in that the first polymeric diol is a polyether diol and the second polymeric diol is a polyester diol. SUMMARY A process for producing polyurethane elastic yarn of a first polymeric diol having a molecular weight of 600 or more, a second polymeric diol which can be the same or different from the first polymeric diol and has a molecular weight of 600 or more, a first low molecular weight diol having a molecular weight of 500 or less, a second low molecular weight diol which may be the same as or different from the first low molecular weight diol, a first diisocyanate and a second diisocyanate which may be the same or different from the first diisocyanate as main starting materials, the total amount of the first diisocyanate and the second diisocyanate in the starting materials being 0.95 to 1.25 times the total molar amount of the first polymeric diol, second polymeric diol, the first diol of low molecular weight and the second diol of low molecular weight, comprising the step of: continuously extruding from a nozzle a polyurethane polymer in the liquid state; This is obtained by continuously reacting a prepolymer having a hydroxyl terminal obtained by reacting the first polymeric diol, the first low molecular weight diol and the first diisocyanate, with a prepolymer having a diisocyanate terminal obtained by reacting the second polymeric diol, the second diol of low molecular weight and the second diisocyanate.