JP2802792B2 - Method for producing copolycarbonate urethane elastic fiber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a copolycarbonate urethane elastic fiber, and more particularly to a method for producing a copolycarbonate urethane elastic yarn excellent in commercial productivity and commercial value. It is.

[Conventional technology]

Conventionally, the main raw materials of urethane elastic fibers industrialized in the world have been limited to three types: an ether type using polytetramethylene glycol, an adipate ester type, and a type using a mixture thereof (“Polyurethane Resin Handbook”). (Pages 512 to 516, edited by Keiji Iwata, published by Nikkan Kogyo Shimbun, September 1987).

However, the ether type was inferior in chlorine resistance and light resistance, while the ester type was low in mold resistance, and the mixed type had both disadvantages.

Known literature on urethane elastic fibers for polycarbonate diols, for example, JP-A-62-184117, JP-A-59-211678 and the aforementioned polyurethane resin handbook (Chapter 13, polyurethane elastic fibers), No. 514
Pp. 515, aliphatic polycarbonate diols (polybutylene carbonate diol and polyhexamethylene carbonate diol) as examples of diol raw materials;
Is disclosed.

JP-A-64-9225 discloses an aliphatic copolycarbonate diol comprising a diol having 6 and 5 carbon atoms.

However, although it has been known that urethane using polycarbonate diol can satisfy light resistance, mold resistance and chlorine resistance, it has been limited to use as a film or a coating material. Until now, there has been no known example in which a polyurethane polymer using only polycarbonate diol as a diol component is spun as a urethane elastic fiber by spinning the polyurethane polymer alone, not as a conjugate yarn or a polymer blend yarn.

The reason for this is that conventionally known homopolycarbonate diols, for example, polyhexamethylene carbonate diol, have high crystallinity, and spinning with a polyurethane polymer alone breaks during spinning, making spinning impossible.

However, when using the polyurethane of Japanese Patent Application No. 62-236728 using the aliphatic copolycarbonate diol of JP-A-64-9225, the spinnability is greatly improved, and usually,
Stable production at about 400 m / min, the dry spinning speed that is commercially produced, becomes possible. However, under the condition of increasing the production efficiency by further performing high-speed spinning, it could not be said that it still has sufficient spinning stability. That is, the storage stability and high-speed spinning stability of the stock solution of the polymer for spinning cannot be said to be in a sufficiently stable state yet, and improvement in yarn physical properties such as elastic recovery and breaking elongation is also desired. Many yarn breaks occurred in knitting processes such as warping and knitting to make (fabric).

Also, the finished fabric surface after the dyeing process lacked uniformity in appearance, resulting in low quality and low commercial value of the product.

[Problems to be solved by the invention]

The present invention is directed to a copolycarbonate urethane elastic fiber useful as a fiber material having excellent durability, i.e., chlorine resistance, light resistance and mold resistance, which enhances commercial productivity and commercial value of the polycarbonate urethane elastic fiber as a fiber. A method for producing a fiber is provided.

[Means for solving the problem]

The present inventors have made intensive studies to solve these problems, and have reached the present invention. That is, in the method of the present invention, the commercial productivity and low commercial value of the conventional polycarbonate-based urethane fiber are due to the high crystallinity of the homopolycarbonate diol used as a raw material, Even aliphatic copolycarbonate diols comprising 6 and 5 carbon atom diols are not at a satisfactory level, and as a result of further studies, surprisingly, diol structural units having 6 and 5 carbon atoms are surprising. Further, the above-mentioned problems relating to commercial productivity and commercial value can be solved by the production method of the present invention using a copolycarbonate diol comprising at least three or more types of structural units in which a third structural unit defined by the present invention is added. They have found that they can be solved, and have reached the present invention.

That is, the present invention provides (Wherein, X is 2 carbon atoms excluding CH _{2 6,} CH _{2 5}
To 10 linear or branched alkylene groups or divalent alicyclic hydrocarbon groups. ) In the structural unit represented by the formula, the ratio of A and B is 70:30 to 30:
70, and the sum of A and B is 80 to 99.9, and the proportion of C selected from at least one or more C is 20 to 0.1, the number average molecular weight is 1500 to 5000, and the terminal is hydroxyl group. A polyurethane polymer obtained by reacting a copolycarbonate diol with an excess of an organic diisocyanate to produce a urethane prepolymer having isocyanate groups at both ends, and then chain-extending with a compound containing two active hydrogens in the molecule A process for producing a copolycarbonate-based urethane elastic fiber, which comprises spinning the composition and applying an oil agent containing an organopolysiloxane as a main component.

The number average molecular weight of the copolycarbonate diol that can be used in the method of the present invention can be determined from the OH number and is generally from 1500 to 5000, preferably from 2000 to 4500, most preferably from 2500 to 4000. In the range exceeding 5,000, elastic recovery as urethane elastic fiber is inferior,
If it is less than 1500, the elongation at break decreases.

The copolycarbonate diol used in the present invention is (Wherein, X is 2 carbon atoms excluding CH _{2 6,} CH _{2 5}
To 10 linear or branched alkylene groups or divalent alicyclic hydrocarbon groups. It is essential to have A, B and C repeating units. A homopolycarbonate diol comprising a single repeating structural unit of each of A, B and C has a high melting point, and the production of urethane elastic fibers using the same and the elastic properties as fibers are extremely low. In addition,
Urethane elastic fibers described in Japanese Patent Application No. 64-9225 and Japanese Patent Application No. 63-190656, starting from a copolycarbonate diol having a repeating unit composed of A and B, are commercially available to the extent that they are usually used. Although stability is improved, production stability under high-speed spinning conditions and the like is not yet sufficient. However, surprisingly, when a copolycarbonate diol consisting of at least three or more structural units including the unit having the structure of C is used in addition to A and B, the commercial productivity of the urethane elastic fiber and The properties as fibers were found to be significantly improved.
As a result of further studying the effects of the present invention, the reason is not sufficiently clear, but the B component added to the A component, that is, the component having 5 carbon atoms contributes to the improvement effect, and further, the C component is added thereto. It was found to be significantly improved.

The proportion of the copolycarbonate structural units A, B and C of the present invention is at least 1 with respect to the ratio of A and B being 70:30 to 30:70 and the sum of A and B being 80 to 99.9. The proportion of C selected from the species of C is 20 to 0.1. In particular, when the ratio of A and B is 60:40 to 40:60 and the sum of A and B is 80 to 98, the ratio of C selected from at least one or more C is 20 to 40. 2 is preferred.

Copolycarbonate diols that can be used in the present invention include:
According to the methods described in Examples 1 to 6 and Comparative Examples 1 to 3 of Japanese Patent Application No. 63-190656, the catalyst can be used alone or in combination from diphenyl carbonate, dimethyl carbonate, ethylene carbonate, or the like as a catalyst. .

According to the method of the present invention, a small amount of an ethylene ether unit (—CH ₂ CH ₂ O—) group may be contained in some cases. However, even if it contains about 20%, the effect of the present invention is not adversely affected.

The copolycarbonate diol that can be used in the method of the present invention is a low-melting point diol, and does not show waxy cloudy solidification seen in polyhexamethylene carbonate diol even at around 20 ° C., even under DSC measurement conditions. No peak is observed.

The raw materials of the polycarbonate diol are A, B and C, respectively.
A diol corresponding to the component, for example, A is 1,6-hexamethylene glycol, B is 1,5-pentanediol, and C is a diol having 2 to 10 carbon atoms other than the diol corresponding to the A and B components. A compound having two hydroxyl groups in one molecule having a linear or branched alkyl group or an alicyclic hydrocarbon group, specifically, ethylene glycol, 1,
3-propanediol, 1,4-butanediol, 1,7-heptanediol, 1,8-octanediol, 2-ethyl-1,6-hexanediol, 2-methyl-1,3-propanediol, neopentyl Glycol, 3-methyl 1,5-
Pentanediol 1,3-cyclohexanediol, 1,4-
Cyclohexanediol, 1,4-dimethylolcyclohexane, 2-methyl-2-butylpropanediol-1,
3-, 2-ethyl-2-butylpropanediol 1,3,1,
Although 10-decanediol and 4,4-dicyclohexyldimethylmethanediol can be used, neopentyl glycol having an alkyl group on both side chains is particularly preferable.

In the present invention, an excess mole of an organic diisocyanate is reacted with the above copolycarbonate diol to produce a urethane prepolymer having isocyanate groups at both ends. As the organic diisocyanate used at this time,
For example, m- and p-phenylenediisocyanate, 2,
4- and 2,6-toluylene diisocyanate, p-xylylene diisocyanate, 4,4'-dimethyl-1,3-xylylene diisocyanate, 1-alkylphenylene-2,4
-And 2,6-diisocyanate, 3- (α-isocyanatoethyl) phenyl isocyanate, 2,6-diethylphenylene-1,4-diisocyanate, diphenylmethane-4,4′-diisocyanate, diphenyl-dimethylmethane-4 , 4'-diisocyanate, diphenyl ether-4,4'-diisocyanate, naphthylene-1,5-diisocyanate, 1,6-hexamethylene diisocyanate, cyclohexylene-4,4'-diisocyanate, 4,
4'-Dicyclohexylmethane diisocyanate 1,3-bis (α, α-dimethyl isocyanatomethyl) benzene, 1,4-bis (α, α-dimethyl isocyanatomethyl) benzene and the like can be mentioned. Preferred is a diisocyanate compound having a benzene ring, and particularly preferred is diphenylmethane-4,4'-diisocyanate.

The excess mole referred to in the present invention means that the ratio of the molar amount of the copolycarbonate diol used in the present invention to the molar amount of the organic diisocyanate is 1: 1.3 to 1: 3.0, preferably 1: 1.5 to 1: 1.
2.5.

As the bifunctional active hydrogen compound, ethylenediamine, 1,
2-propylenediamine, hexamethylenediamine, 1,4
-Cyclohexyldiamine, 1,3-cyclohexyldiamine, 1,4-tetrachloro-xylylenediamine, 1,3-
Tetrachloro-xylylenediamine, 1,4-xylylenediamine, 1,3-xylylenediamine, 4,4'-diphenylmethanediamine, hydrazine, 1,4-diaminopiperazine, ethylene glycol, 1,4-butane Diol, 1,8
-One kind of hexaneisole, water and the like, or a mixture of two or more kinds thereof. Preferred are diamines, with ethylene diamine being particularly preferred. The production of the urethane polymer may be performed in the presence or absence of a solvent. In that case, examples of the solvent for polyurethane include N, N-dimethylformamide, N, N-dimethylacetamide, tetramethylurea, hexamethylphosphonamide and the like.

Usually, 1.3 to 3.0 moles of an organic diisocyanate is reacted in the presence or absence of a solvent with respect to 1 mole of the polymer diol to obtain a urethane prepolymer having both ends of an isocyanate group. In this case, a catalyst for accelerating the reaction of a tertiary amine or a tin compound or an acidic negative catalyst can be used.

Subsequently, a chain extension reaction is performed with a bifunctional active hydrogen-containing compound to obtain a polyurethane solution.

The polymer obtained by extending the chain of the urethane prepolymer with a bifunctional active hydrogen-containing compound may be terminated with a monofunctional active hydrogen-containing compound such as an amine or alcohol and alkylhydrazines by a conventional method.

In the present invention, an antibacterial agent, a fungicide in polyurethane,
Additives such as leveling agents and other commonly added hindered phenols, hindered amines, ultraviolet absorbers, tertiary amine compounds, gas discoloration inhibitors, pigments such as titanium oxide can be used in combination.

After the copolycarbonate-based urethane polymer obtained in the present invention is arbitrarily mixed with a commonly used ether-based or ester-based urethane polymer, the spun fiber has the advantage of improving the durability, which is a drawback of each. In that case, it is preferable to mix with an ester-based urethane polymer from the viewpoint of compatibility between the polymers.

The copolycarbonate-based urethane polymer solution obtained from the present invention can be spun by a dry, wet or melt spinning method of information, but dry spinning is preferred.

 The spun yarn is false twisted and an oil agent is applied.

In addition to the dimethylpolysiloxane used in the present invention,
A diorganopolysiloxane in which a part of a methyl group is substituted with another alkyl group or a phenyl group, an epoxy group, an amino group,
An oil based on an organopolysiloxane such as a modified polysiloxane having a vinyl group introduced therein or a mineral oil is preferred. Particularly, for polyurethane using copolycarbonate diol as a soft component, straight oil mainly composed of organopolysiloxane is particularly preferable.

The copolycarbonate urethane elastic fiber produced by the method of the present invention is particularly useful as a material for swimming or fashion swimwear worn in indoor and outdoor pools.

The reason why the method of the present invention can provide a copolycarbonate-based urethane elastic fiber having excellent commercial productivity and high commercial value is not fully understood, but the elastic fiber is different from a general resin molded product. In addition, the processing (spinning) process and the product (knitting) process are extremely difficult, so that the required quality for the raw material dial is required to be much more severe than that of the resin molded product. Since the diol component, which accounts for about 70% of the raw material of the urethane elastic fiber, is extremely non-crystalline, the diol component is used in the polymerization stock solution before spinning and in the orientation elongation during spinning and during the elongation in the product (dough) process after spinning. It is important to note that the method of the present invention provides a non-crystalline material until it has the first commercial meaning as a copolycarbonate urethane elastic fiber by the copolycarbonate diol comprising at least three types of structural units of A, B and C. It is presumed that the sex level was increased.

 Next, the evaluation method of the present invention will be described.

Viscosity stability of stock solution: Put the polymer stock solution for spinning in a sealed container in which the solvent does not scatter, and leave it in a 30 ° C safety oven (Tabayespec Co., Ltd. product name SPS-222 type) for 30 days after leaving it for 7 days.
Using a viscometer (EHD type, manufactured by Tokyo Keiki Co., Ltd.) using the viscometer (viscosity after putting in a safety oven), and the difference between the viscosity of each stock solution for polymer spinning and the viscosity before putting in a safety oven (Poise / 30 ° C.) was used as a measure of stability.

Spinnability: The spinnability test was performed using a stock solution immediately after polymerization but before thickening over time.

In dry spinning, a winding speed of 40 denier / 5 filament is fixed at Ym / min once for 3 minutes, and then the winding speed is gradually increased, and the winding speed at the time when yarn breakage occurs in the spinning cylinder. The spinning stability (spinnability) of the spinning stock solution was evaluated using the ultimate single yarn denier per filament calculated from Xm / min and the following formula.

As the denier per filament is smaller, the spinning solution has higher spinning stability at high speed spinning.

Y is the initial winding speed (starting speed) (m / min).

 X is a winding speed (m / min) at the time of yarn breakage.

In Table 1, the initial speed was 400 m / min (Y = 400). In Table 3, the evaluation was performed at an initial speed of 600 m / min (Y = 600).

Breaking strength, elongation; Tensile tester (trade name: UTM-III-, Orientec Co., Ltd.)
100 type) at a temperature of 20 ° C. and a humidity of 65%.

This is the value at the time of sample breakage when the sample length of 5 cm is extended at a strain rate of 1000% / min.

Elastic recovery rate: Measured under the same conditions using the same tensile tester as above.

This is the value of the third residual strain when the elongation recovery up to 300% is repeated three times at a strain rate of 1000% / min for a sample having a sample length of 5 cm. The residual strain is a strain (%) from a sample length of 5 cm when the stress at the time of recovery becomes 0 (shown in FIG. 1).

Chlorine resistance: A sample length of 10 cm is stretched by 50%, and a scouring agent (KAO-ATLAS) (trade name: Score Roll C-75) is 2 g / pH with acetic acid and ammonium acetate.
After boiling for 60 minutes in an aqueous solution adjusted to = 4, washing with water and 45 ° C
The sample dried at 30 ° C is circulated at a flow rate of 3.0 cm / sec 3
It was immersed in a container containing an aqueous solution of sodium hypochlorite adjusted to a ppm concentration, a sample was taken out every immersion time, and the breaking strength was measured, and the breaking strength was reduced to half of the breaking strength before the treatment. The immersion time (hr) at the time point.

Lightfastness: A 40 denier polyurethane elastic fiber was irradiated with ultraviolet light by a fade meter manufactured by Suga Test Instruments Co., Ltd. to measure the half-life of the yarn strength after washing. The washing process is as follows: 40 denier polyurethane fiber is boiled in water under 50% elongation for 1 hour, and then a commercially available detergent (Kao Co., Ltd. brand new beads) dissolved in a 1.3 g / washing liquid. Washing was performed at 40 ° C. for 40 minutes, followed by washing with water and drying at 45 ° C. for 15 minutes.

Mold resistance: A circular knitting machine (Koike Kikai Seisakusho Co., Ltd. model name TN)
-7), create a circular knitted fabric with knitting draft 1.45,
Wrap it in a cloth soaked sufficiently in water, and place it in a thermo-hygrostat (30 ℃ × 90
% RH condition), and visually inspected the pinholes of the knitted fabric due to the occurrence of mold, and evaluated the number of days from the standing until the occurrence of pinholes.

Evaluation of process performance: Number of yarn breakage after aging The number of yarn breakage during aging when a 40 denier yarn was warped under the following conditions was measured using a warping machine manufactured by River Germany. The number of products in process was 600 cheese, the warping length was 45,000, the positive feed creel speed was 75 m / min, the beam speed was 150 m / min, the pre-stretch was 145%, and the beam stretch was 100%.

Number of yarn breaks during knitting Using a tricot knitting machine manufactured by Karl Meier, West Germany, using 50 denier nylon as the mating material, the runner speed is 160 m / min for the front of the nylon yarn and 80 m / min for the back of the urethane elastic fiber. The number of yarn breaks when knitting 20-way two-way tricot fabrics was measured.

Finished fabric quality after dyeing: After dyeing the 2-way tricot fabric knitted by the above method under the following conditions, the appearance uniformity of the finished fabric surface is evaluated in three stages of A, B, and C after 2 hours. Was evaluated.

 Class A: uniform without dyeing unevenness Class B: partially non-uniform part C class: non-uniform part is noticeable on the entire surface

(1) Pre-wet process; scouring agent (KAO-ATLAS) (trade name, score roll C-75) 2 g /
The dough is immersed in a bath containing an aqueous solution (50 ° C) adjusted to a concentration of 10 seconds, and then boiled (90-95 ° C) with water.
Perform for 30 seconds.

(2) Presetting step: treatment at 190 ° C. for 50 seconds with a pin tenter type baking device
Fit well 80 ± 3).

(3) Dyeing process: 3.0 g of dye (Bayer Japan K.K. brand name Blankophor CL) /3.0 g of dyeing aid (Sanyo Kasei K.K.
The dough is placed in an aqueous solution prepared by adjusting the aqueous solution prepared at a bath ratio of 1: 5 to pH = 4.0 with acetic acid and sodium acetate at 80 to 85 ° C., and dyed for 2 hours.

(4) Final setting step: Treating with a pin tenter type baking device at 180 ° C for 30 seconds
± 3, fit well 70 ± 3).

Number average molecular weight: The number average molecular weight of the polycarbonate diol was determined from the OH value. The ratio of the components A, B and C is determined by a general method of measuring the corresponding alcohol by GC or LC after decomposing the strong alkali diol, or the reaction amount and the unreacted amount with respect to the raw materials used in the production of the diol. Measurement or
It can be determined by any of the measurements by NMR or a method of combining them.

The number average molecular weight of the polycarbonate diol is calculated by the following equation.

Number average molecular weight (M) = 112200 / OH value Measurement of OH value Pyridine anhydride solution (42 g of phthalic anhydride / pyridine)
300 cc) was weighed accurately (W _S ) in an Erlenmeyer flask, and about 5 g of a sample (polycarbonate diol) was precisely weighed (S). A condenser was attached to the upper part of the Erlenmeyer flask and placed in a 100 ° C. glycerin bath for 2 hours. Let react.

Next, after cooling to room temperature, an aqueous pyridine solution (pyridine
Inject about 20 g of 200 cc / 100 cc of distilled water including the washing solution from the top of the cooling tube and mix thoroughly. The same operation as blank test, without taking samples only subjected to phthalic anhydride pyridine solution amount at that time and (W _B). Then, 0.5N-KOH
Titrate with ethanol solution. (L _S ) Titrate the blank test in the same manner. (L _S ) The calculation of the OH value is represented by the following equation.

f; titer of 0.5-KOH ethanol solution S; amount of polycarbonate diol (g) W _B ; amount of pyridine anhydride phthalate solution for blank test (g) W _S ; amount of pyridine anhydride phthalate solution to react with sample (g) l _B ; titration of blank test (ml) l _s ; titration of sample (ml) [Example] Composition in urethane polymerization is copolycarbonate diol: 4,4'diphenylmethane diisocyanate at 1: 1.96.
Molar ratio, diethylamine: ethylenediamine 4.6: 95.4
Polymerization was carried out in a molar ratio. The number average molecular weight of the polycarbonate diol used in this example and the comparative example was 2500 to 4000, and the number average molecular weight of the polytetramethylene glycol of the comparative example was 2000, and the polyester diol (adipic acid: ethylene glycol: 1.00 for 1,4 butanediol:
(0.6: 0.4 molar ratio) means that both ends are hydroxyl groups and the number average molecular weight is 2
Using a sample of 500, urethane polymerization was carried out according to the above composition and in accordance with the following typical example of urethane polymerization.

Representative examples of urethane polymerization include copolycarbonate diols having hydroxyl groups at both ends (A: 65, B: 32, C 1800 g of a number average molecular weight of 3600), 240 g of 4,4'-diphenylmethane diisocyanate, and 1150 g of N, N'-dimethylacetamide were reacted while stirring at 40 ° C. for 3 hours in a stream of nitrogen gas. , N'-Dimethylacetamide solution was obtained. Then, after cooling this to room temperature, dried N, N'-dimethylacetamide 1
900 g was added and dissolved at room temperature with stirring to obtain a uniform prepolymer solution.

Separately, a solution consisting of 26.9 g of ethylenediamine, 3.13 g of diethylamine and 1780 g of N, N'-dimethylacetamide is prepared, and the prepolymer solution is added dropwise thereto with vigorous stirring. The viscosity gradually increased at the same time as the dropwise addition, and after completion of the dropwise addition, the mixture was stirred for about 30 minutes to obtain a 1200 poise viscous liquid at 30 ° C.

The viscosity after the urethane polymerization reaction using the various diols of Examples 1 to 7 and Comparative Examples 1 to 6 and Examples 8 to 12 and Comparative Examples 9 to 10 shown in Tables 1 to 3 was 30 ° C., and the polymer concentration was 30.
% (N, N 'dimethylacetamide solution), 1600-1200
It was a poisony viscous liquid.

Examples 1 to 7 and Comparative Examples 1 to 8 The above-mentioned urethane polymerization solution was dry-spun at a spinning speed of 400 m / min, and an oil agent containing dimethylpolysiloxane as a main component (10
cst) by 6% by weight based on the urethane elastic fiber,
Shown in Examples 1 to 7 and Comparative Examples 2 to 6 in Tables 1 and 2
A 40 denier urethane elastic fiber was obtained.

The breaking strengths of these urethane elastic fibers (Examples 1 to 7 and Comparative Examples 2 to 6) were all excellent in the range of 60 to 65 g.

The urethane elastic fibers obtained in Examples 1 to 7 and Comparative Examples 2 to 6 were evaluated for commercial productivity and commercial value. Table 1 shows the results.

Furthermore, Examples 1-3 and 5-6 and Comparative Examples 3,7
, And 8 were evaluated for durability. Table 2 shows the results.

Examples 8 to 12 and Comparative Examples 9 and 10 Urethane polymerization solutions were obtained in the same manner as in the above Examples.

Further, as shown in Table 3, dry spinning was performed at a spinning speed of 600 m / min.
By adding 6% by weight of t) to the urethane elastic fiber, 40 denier urethane elastic fibers of Examples 8 to 12 and Comparative Examples 9 and 10 were obtained.

The breaking strength of these yarns was all excellent within the range of 60 to 65 g. Using these yarns, the commercial stability and commercial value, the process performance and the quality of the finished fabric after dyeing were explained. Table 3 shows the results.

[Effects of the Invention] By the production method of the present invention, urethane elastic fibers having high commercial value can be obtained under low-cost commercial production stability, especially high-speed commercial production stability. This fiber is extremely useful as a urethane elastic fiber material for water use, which simultaneously solves the drawbacks of the conventional ether-based and ester-based urethane elastic fibers, which are chlorine resistance, light resistance, and mold resistance. is there.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between stress and strain for explaining the elastic recovery rate.

Claims (2)

(57) [Claims] (1) As a repeating unit (Wherein, X is 2 carbon atoms excluding CH _{2 6,} CH _{2 5}
To 10 linear or branched alkylene groups or divalent alicyclic hydrocarbon groups. ) In the structural unit represented by the formula, the ratio of A and B is 70:30 to 30:
70, and the sum of A and B is 80 to 99.9, and the proportion of C selected from at least one or more of C is 20 to 0.1 and the number average molecular weight is 1500 to 5000. Was reacted with an excess molar amount of organic diisocyanate to a copolycarbonate diol consisting of hydroxyl groups to produce a urethane prepolymer having isoyanate groups at both ends, and then chain-extended with a compound containing two active hydrogens in the molecule. A method for producing a copolycarbonate urethane elastic fiber, comprising spinning a urethane polymer and applying an oil agent containing an organopolysiloxane as a main component. 2. The method for producing a copolycarbonate urethane elastic fiber according to claim 1, wherein the number average molecular weight of the copolycarbonate diol is 2500 to 4000.