JP3247777B2 - Polyurethane elastic body and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-quality thermoplastic polyurethane elastomer and a method for continuously producing the same.

[0002]

2. Description of the Related Art Various methods are known for a bulk polymerization method for producing a thermoplastic polyurethane in the absence of a solvent. A typical example is a method of producing a polyurethane elastic body by reacting a polymer glycol and a diisocyanate compound in a kneader such as a kneader (Japanese Patent Publication No. Sho 3).
No. 9-17093) and a labor-saving and energy-saving production method for continuously producing a polyurethane resin (Japanese Patent Publication No. 43-52).
No. 90 publication).

However, it is very difficult with the conventional manufacturing method to strictly control the ratio of the raw materials to be charged for each batch, the processing temperature, the processing time, and the regulation of the water content.
For this reason, it is extremely difficult to make the product uniform. In addition, when the polyurethane obtained by the above method is melt-spun, there are a number of gel-like substances that impede the passage of nozzle holes and filters, and it is difficult to spin for a long time. Good products could not be obtained stably due to formation.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-quality polyurethane elastic body having extremely few fish eyes,
And to provide a continuously stable and industrially advantageous method.

[0005]

Means and Action for Solving the Problems The present inventors have made intensive studies to solve the above problems,
It has been found that a polyurethane elastic body that can achieve the object of the present invention can be produced only by the limited method as described below, and the present invention has been completed.

That is, the polyurethane elastic body of the present invention is a thermoplastic polyurethane elastic body produced by a bulk polymerization method, and has a peak having a molecular weight of 770 as an apex in a molecular weight distribution curve of a hard segment collected by alkali. The ratio of the intensity to the intensity of the peak having a molecular weight of 1790 as an apex is in the range of 1.02 : 1 to 1.08 : 1 .

A second aspect of the present invention is a polyurethane elastic fiber comprising the above polyurethane elastic body.

The polyurethane elastic body and polyurethane elastic fiber of the present invention further contain not more than 200 fish eyes based on a polyurethane substrate per kg of polyurethane. It should be understood that fisheye based on a polyurethane substrate is used in a meaning that does not include additives added to polyurethane, for example, fillers, matting agents such as titanium oxide, or unintentionally contained insolubles (dust). is there. The preferred ratio of fish eyes is 100 or less per kg of polyurethane.

[0009] Fisheye based on polyurethane substrates, according to the work of the present inventors, shows that (a) 5 ° C at 20 ° C.
A crystal grain having a size of about 50 μm and melting at a melting point (Tm) of a homopolymer composed of only a hard segment constituting a polyurethane substrate, or (b) having a size of 5 μm or more at 20 ° C. However, it was revealed that the gel was not melted at the melting point Tm. The former can be confirmed by observing with a polarizing microscope that the crystallized portion of the hard segment in the polyurethane elastic material develops color (birefringence) and disappears when heated to the crystal melting point Tm of the polymer comprising the hard segment. The size of the crystallized part of this hard segment is 5μ.
For example, in the case of 1,4-butanediol and 4,4′-diphenylmethane diisocyanate, the crystal grains having a crystal melting point of 245 ° C. to 260 ° C. are usually melt-spun at 200 ° C. to 240 ° C. Even if it is melt-extrusion molded, it remains as it is on the fiber or film and becomes fisheye or its core, spun yarn breakage, poor unwinding of the wound body due to remarkable stickiness, perforation of knitted fabric, weft step or film fisheye Large crystal grains that do not pass through the filter, for example, those having a size of about 40 μm or more, cause an increase in filtration pressure. On the other hand, a gel-like substance having a size of 5 μm or more which does not disappear even at the crystal melting point develops weaker color than crystal grains and is often amorphous.
Further, the gel-like substance remains as an insoluble substance when dissolved in a solvent for the polyurethane elastic body. This gel-like substance passes through a filter and a nozzle hole, but becomes a fisheye such as a fiber or a film or a core thereof as in the case of crystal grains, and causes trouble. In other words, when the knitting is released from the wound body in the subsequent process, the nylon yarn is covered with the polyurethane yarn in the step of covering the polyurethane yarn, the yarn breaks due to the single yarn breakage of the polyurethane yarn or the heat of the dyeing step, the deterioration of the yarn physical properties and the yarn It causes non-uniformity and uneven dyeing of the knitted fabric due to the non-uniformity. Furthermore, when knitting, yarn breakage during the process of releasing from the wound body,
It causes dye unevenness and weft. On the other hand, a colored portion having a size of less than 5 μm does not cause the above-mentioned trouble.

In the present invention, the method of fractionating the hard segment, the method of measuring the molecular weight distribution thereof, the method of measuring the reactivity of the polyester diol, and the fish eye based on the polyurethane substrate are those obtained by the following methods. Hard segment fractionation: 0.01% by weight KO at 50 ° C
The polyurethane was immersed in an H-methanol solution so as to be 1% by weight, left standing for 24 hours, poured into water, and the precipitate was filtered and dried to obtain a hard segment fraction. Molecular weight distribution curve: Waters 710 type fully automatic sample processor, 590 type multipurpose pump, 481 type tunable ultraviolet detector, and G2500HHR manufactured by Tosoh Corporation
Gel permeation chromatography equipped with three mold-packed columns, using dimethylformamide as a solvent, 0.35% by weight, column temperature 50 ° C., ultraviolet 280 n
The molecular weight distribution curve was obtained by measuring the absorption intensity at m. Polystyrene (peak molecular weight = 580,95) was used as a standard sample.
0, 1250, 1700, 2450, 3600, 505
0) was used. The measured peak molecular weight of the sample is equivalent to standard polystyrene. Reactivity measurement: 300 g of molten polyester is weighed in a 500 ml beaker. The temperature of the polyester is adjusted to 82 ° C. with stirring while passing nitrogen gas over the liquid surface. Oil bath temperature 82 ±
After the temperature is adjusted to 0.5 ° C., MDI at 70 ° C. is added, and the mixture is stirred at about 500 rpm for 1 minute. Next, the stirrer was removed, and the MD was measured using a BM type viscometer (rotor No. 4).
The time from the addition of I to 500 poise is indicated as reactivity. Fisheye measurement method: sheet, film (thickness is 20
Fish eyes of 5 μm or more are counted with a microscope. The fiber (usually, the diameter is 2
About 0 μm to 70 μm)
The distance between them and use the strain gauge
More than 100 μm is detected and measured.

The method for producing a polyurethane elastomer according to the present invention is characterized in that an organic diisocyanate and a high-molecular diol are reacted in advance to form a prepolymer, and then the prepolymer and a low-molecular diol are mixed and reacted to form a lump. In producing a thermoplastic polyurethane elastic body by a polymerization method, a polyester diol and an organic diisocyanate are mixed in a constant temperature bath at 80 ° C. such that a molar ratio of an isocyanate group in an organic isocyanate to a hydroxyl group in the polyester diol becomes 1.07. When I let go,
It is characterized by using a polyester diol in which the time for the mixture to reach 500 poise is in the range of 80 to 90 minutes.

The polyester diol used in the present invention includes ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol and 2-methylpropane. Obtained by condensation polymerization of diol or other low molecular weight diol with low molecular weight dicarboxylic acid such as glutanic acid, adipic acid, pimelic acid, suberic acid, sebacic acid, terephthalic acid, isophthalic acid, or ring-opening polymerization of lactone. Polylactone diols, for example, polycaprolactone glycol, polypropiolactone glycol, polyvalerolactone glycol and the like. Of these polyester diols, 1,4-
The polyurethane elastic body of the present invention produced using a product obtained from polycondensation of butanediol and adipic acid or a product obtained from polycondensation of 1,6-hexanediol and adipic acid particularly has a fisheye It is suitable for films and fibers because it hardly reduces the strength, elongation, elastic modulus, elongation recovery rate, etc. when heat set.

The average molecular weight of the polyester diol is usually from 500 to 3,000, preferably from 500 to 250.
It is better to be within the range of 0. If the average molecular weight is too small, the compatibility with the organic diisocyanate is too good, and the elasticity of the produced polyurethane is poor. On the other hand, if the average molecular weight is too large, the compatibility of the organic diisocyanate becomes poor and mixing in the polymerization step is difficult. And a stable polyurethane cannot be obtained because fish eyes are easily generated. In the present invention, it is necessary that the reactivity of the polyester diol is in the range of 80 to 90 minutes. In the case of less than 80 minutes, the molecular weight of the hard segment is small and fish eyes are easily formed,
On the other hand, if the time exceeds 90 minutes, the prepolymer formation reaction is insufficient, and the yarn is liable to be formed when poor threading is caused (the number of fine yarn portions causing yarn breakage due to hot water in the dyeing step increases). Further, a more preferable result is shown by mixing a polycondensate of 1,4-butanediol and adipic acid and a polycondensate of 1,6-hexanediol and adipic acid, which enhance the advantageous effects of the present invention. If only a polycondensate of 1,4-butanediol and adipic acid is used, the reaction time tends to be short. Conversely, if only a polycondensate of 1,6-hexanediol and adipic acid is used, the reaction time is long. Tend to be difficult to control between 80 and 90 minutes. Therefore, the mixing ratio between 1,4-butanediol and 1,6
Most preferably, the hexanediol is between 2: 8 and 7: 3 by weight.

The low molecular diols include ethylene glycol, propylene glycol,
4-butanediol, 1,5-pentaneglycol, 3
Aliphatic and aromatic diols such as -methylpentane glycol, 1,6-hexanediol, and 1,4-bishydroxyethylbenzene. These may be used alone or as a mixture of two or more.

According to the method described in JP-B-43-5920, a mixture of the above-mentioned polymer diol and low-molecular diol is reacted with the organic diisocyanate at a time. A homogeneous polyurethane elastomer cannot be obtained due to the difference in reactivity of the molecular diol. However, by using a prepolymer method in which the organic diisocyanate and the polymer diol are reacted in advance, a homogeneous polyurethane elastic body can be stably obtained.

The ratio of the high molecular diol, the low molecular diol and the organic diisocyanate used is determined by the molar ratio (R) of the isocyanate group in the organic diisocyanate to the hydroxyl group in all diols of the high molecular diol and the low molecular diol.
Is preferably in the range of 0.95 to 1.05. If the R value is out of this range, the resulting polyurethane elastic body cannot be obtained in terms of physical properties and melt moldability, and contains many fish eyes, which is not preferable.

In the polymerization of the polyurethane elastomer, the prepolymer and the low molecular weight diol are first uniformly mixed and then supplied to a screw type extruder. As a screw-type extruder, a twin-screw extruder is suitable because of its high kneading effect. Usually, by performing the mass melt polymerization at a screw rotation speed of 30 to 300 rpm, a cylinder temperature of the polymerization zone of 210 to 245 ° C., and a tip extrusion pressure of 20 to 45 kg / cm ² , the gel-like material is reduced and the variation of the hard segment is reduced. A less high-quality polyurethane resin can be obtained.
The average residence time depends on the screw and L / D, but is usually 2 to 20 minutes and the extrusion is carried out continuously from the outlet.

When a polyurethane elastic body or a fiber or film thereof is produced according to the present invention, a finely divided colorant, antioxidant, lubricant, weathering agent, heat-resistant agent, etc. may be added to the extruder through a hopper opening, if necessary. It can be added or evenly dispersed in the prepolymer. When a prepolymer and a low molecular weight diol are mixed to increase the molecular weight, a known polymerization catalyst such as dibutyltin laurate or N-methylmonophorine may be dispersed in the low molecular weight diol and used.

[0019]

According to the production method of the present invention, a high-quality polyurethane elastic body having a very small amount of fish eyes and a small variation in the ratio of low-molecular-weight hard segments can be continuously and stably produced in a short time. can do. Further, the polyurethane elastic body of the present invention is excellent in melt-molding properties, and is particularly useful in yarn knitting during spinning with fisheye, and in knitted articles such as stockings, swimwear, and inners using fisheye-containing yarn, and weft steps. Further, it is useful as a polyurethane elastic fiber which can eliminate yarn breakage due to heat in a dyeing step or the like and non-uniformity of a product caused by a decrease in yarn physical properties.

[0020]

【Example】

Example 1 A polyester diol as a raw material was composed of adipic acid and 1,6
-Polyhexanediol adipate (hereinafter referred to as PHA, molecular weight 2012) obtained by condensation polymerization of hexanediol. The reactivity of this polyester diol is 4,4'-diphenylmethane diisocyanate (hereinafter referred to as MDI). Molar ratio of 1: 1.0
7. When mixed in a constant temperature bath of 80 ° C, 500 poise
The arrival time was 85.4 minutes.

A product obtained by previously melting 63.7 parts by weight of the polyester diol and 29.0 parts by weight of MDI at 70 ° C. in a regulating tank equipped with a stirrer kept at 80 ° C.
The reaction was allowed to proceed for a period of time to prepare a prepolymer. Next, 1,4-butanediol (1,4-B
Using D), it was prepared in a storage tank at 80 ° C. 18.7 kg / h and 1.3 kg / h are continuously supplied from each tank by a measuring pump and mixed by a high-speed mixer.
The mixture was injected into a twin-screw extruder (rotating in the same direction) and polymerized. The cylinder temperature of the twin screw type extruder is 160 ° C., 180 ° C., 220 ° C., 240
° C and 210 ° C, the screw rotation speed was 150 rpm, and the extrusion pressure was 35 kg / cm ² . The polymerized molten polyurethane elastic body was extruded into water from a 2.4 mmφ 2-hole die, and pellets could be obtained stably with a pelletizer.

Next, the pellets were dehydrated and dried to reduce the water content to 80 ppm or less. Then, the hard segments were fractionated with an alkali, and the molecular weight distribution curve of the hard segments was obtained by gel permeation chromatography. In the obtained molecular weight distribution curve, the ratio of the peak intensity at the peak of molecular weight 770 to the peak intensity at the peak of molecular weight 1790 is 1.0.
5: 1.

The pellets were melt-spun using a 25 mmφ single screw extruder at a head temperature of 190 ° C. and 30 denier 1 filament × 8. As a result, there was no change in the filtration pressure during spinning. Was also homogeneous.

Example 2 PHA having a different reactivity from Example 1 (molecular weight: 2036,
A polyurethane elastic monofilament was produced in the same manner as in Example 1 except that the reactivity was 82.6 minutes.

Example 3 The cylinder temperature of a twin screw extruder was set to 160
° C, 190 ° C, 220 ° C, 220 ° C, 210 ° C, PHA
Polyurethane elastic monofilaments were produced in the same manner as in Example 2, except that the ratios of MDI and MDI were changed to 64.2 and 28.5 parts by weight, respectively.

Example 4 A polyurethane elastic monofilament was produced in the same manner as in Example 1 except that the ratio of PHA to MDI was changed to 66.0 and 26.7 parts by weight, respectively.

Comparative Example 1 PHA having a different reactivity from Example 1 (molecular weight 2021,
(73.2 minutes of reactivity), and a polyurethane elastic material was polymerized in the same manner as in Example 1. A monofilament was produced in the same manner as in Example 1 using the obtained polyurethane elastomer pellets.

Comparative Example 2 PHA (molecular weight: 2056,
Polymerization of a polyurethane elastic material was carried out in the same manner as in Example 1 using the reactivity of 98.5 minutes). A monofilament was produced in the same manner as in Example 1 using the obtained polyurethane elastomer pellets.

Comparative Example 3 The cylinder temperature of the twin-screw extruder was set to 150
℃, 170 ℃, 180 ℃, 190 ℃, 190 ℃, PHA
Polyurethane elastic monofilaments were produced in the same manner as in Comparative Example 2, except that the ratio of MDI to MDI was changed to 66.0 and 26.7 parts by weight, respectively.

Example 5 After the dried pellets of Example 1 were melted by an extruder,
From a slit die on a quenching rotary drum to produce a sheet having a thickness of 0.6 mm. When the fisheye of this sheet was measured, it was a very small high quality sheet of about 60 pieces per kg.

[0031]

[Table 1]

[0032]

[Table 2]

Example 6 A polyester diol used as a raw material was adipic acid and 1,4
-Butanediol, and a mixture of polybutanediol adipate (PBA) and polyhexanediol adipate (PHA) obtained by condensation polymerization of 1,6-hexanediol (weight ratio 6: 4, molecular weight 2)
023), and the reactivity of this polyester diol is 4,4'-diphenylmethane diisocyanate (MD
When it was mixed with I) at a molar ratio of 1: 1.07 in a thermostat at 80 ° C., the time to reach 500 poise was 81.5 minutes. Pellets of polyurethane elastomer were produced in the same manner as in Example 1 except that the above-mentioned mixed polyester diol was used. The molecular weight distribution of the hard segment of this polyurethane is such that the ratio of the peak intensity having a molecular weight of 770 at the peak to the peak intensity having a molecular weight of 1790 at the peak is 1.
03: 1.

Using these pellets, melt spinning was performed in the same manner as in Example 1, and there was no change in the filtration pressure during spinning.
The obtained polyurethane elastic monofilament was also homogeneous.

Example 7 Polyurethane elasticity was obtained in the same manner as in Example 6, except that a PBA / PHA mixture having a different reactivity (weight ratio 5: 5, molecular weight 2009, reactivity 88.4 minutes) was used. A body pellet was produced and then the monofilament.

Example 8 The cylinder temperature of a twin screw extruder was set to 160
C., 190.degree. C., 220.degree. C., 220.degree. C., 210.degree. C. and a polyurethane in the same manner as in Example 7, except that the ratio of the polyester diol PBA / PHA mixture and MDI was changed to 64.2 and 28.5 parts by weight, respectively. Elastic pellets and their monofilaments were produced.

Example 9 The ratio of the PBA / PHA mixture to MDI was 66.
A polyurethane elastic pellet and a monofilament thereof were produced in the same manner as in Example 6, except that the amounts were changed to 0 and 26.7 parts by weight.

Comparative Example 4 PBA having a different reactivity from Example 6 (molecular weight 2019,
A polyurethane elastic pellet and a monofilament thereof were produced in the same manner as in Example 6 using the reactivity of 70.1 minutes).

Example 10 PBA / PHA (mixing ratio 1: 9, molecular weight 2020, reactivity 89.0 minutes) having a different reactivity from Example 6 was used.
In the same manner as in Example 6, pellets of polyurethane elastic material and monofilaments thereof were produced.

Example 11 Using PBA / PHA (mixing ratio 8: 2, molecular weight 2045, reactivity 80.3 minutes) having a different reactivity from that of Example 6,
In the same manner as in Example 6, pellets of polyurethane elastic material and monofilaments thereof were produced.

Example 12 The dried pellets of Example 6 were melted by an extruder,
From a slit die on a quenching rotary drum to produce a sheet having a thickness of 0.6 mm. When the fisheye of this sheet was measured, it was a very small number of good sheets of about 40 per kg.

[0042]

[Table 3]

[0043]

[Table 4]

[Brief description of the drawings]

FIG. 1 is an example of an apparatus for producing a urethane elastic body suitable for the present invention.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mutsuhisa Furukawa 1-114 Bunkyo-cho, Nagasaki-shi, Nagasaki Pref. Inspector, Nagasaki University Faculty of Engineering Harue Tanaka (56) References JP-A-60-115616 (JP, A) Japanese Patent Application Laid-Open No. Hei 4-209619 (JP, A) JP-A-61-111318 (JP, A) Japanese Patent Publication No. 49-12597 (JP, B1) Japanese Patent Publication No. 43-1880 (JP, B1) (58) Int.Cl. ⁷ , DB name) C08G 18/42 C08G 18/10

Claims (5)

(57) [Claims] 1. A peak having a molecular weight of 770 as an apex in a molecular weight distribution curve obtained by gel permeation chromatography of a hard segment in a polyurethane which is a thermoplastic polyurethane produced by a bulk polymerization method. Of the peak having a molecular weight of 1790 as the peak is 1.02: 1 to 1.0.
8: 1 polyurethane elastic body. 2. The thermoplastic polyurethane elastic body according to claim 1, wherein the polyurethane eye contains no more than 100 fish eyes of 5 μm or more based on the polyurethane substrate per 1 kg of polyurethane. 3. A polyester diol and an organic diisocyanate are reacted in advance to form a prepolymer, and then the prepolymer and a low molecular weight diol are mixed and reacted to produce a thermoplastic polyurethane by a bulk polymerization method. When the polyester diol and the organic diisocyanate were mixed in a constant temperature bath at 80 ° C. such that the molar ratio of the isocyanate group in the organic isocyanate to the hydroxyl group in the mixture was 1.07, the time required for the mixture to reach 500 poise was 80%. ~ 9
A method for producing a polyurethane elastic body, comprising using a polyester diol having a range of 0 minutes. 4. The molar ratio of isocyanate groups in organic diisocyanate to hydroxyl groups in all diols is 0.95.
4. The method according to claim 3 , wherein the polymerization is carried out so as to fall within a range of from 1.05 to 1.05. 5. A polyester diol obtained by mixing a polycondensate of 1,4-butanediol and adipic acid with a polycondensate of 1,6-hexanediol and adipic acid in a weight ratio of 2: 8 to 7: 3. The method according to claim 3 , wherein the method is used.