JP2773943B2 - Heat resistant polyurethane elastic yarn - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a polyurethane elastic yarn, and more particularly to a polyurethane elastic yarn having excellent heat resistance obtained by a melt spinning method.

<Conventional technology> Polyurethane elastic yarn, so-called spandex Heat resistance
The properties are determined by the production method such as dry, wet or melt spinning.
It is known to be significantly affected. this house,
Yarn obtained by dry and wet spinning is hard segment
Chain extenders so that domains can create strong hydrogen bonds
Diamine is used as the
I'm up. On the other hand, the yarn obtained by the melt spinning method is
A strong hard case is used to melt the thermoplastic polyurethane once.
No fragmentation, recovery from high temperatures, resistance, etc.
Has a significantly lower heat resistance than the two-spun yarn.
I have.

Considering the creep curve of temperature-elongation as one measure of this heat resistance, a yarn without heat resistance will creep at a low temperature, that is, the amount of elongation will increase sharply, and a yarn with heat resistance will have a high temperature. Does not creep to area. Focusing on this creep behavior, a yarn obtained by melt-spinning a thermoplastic polyurethane as it is has a creep behavior as shown in I of FIG. 1, but a yarn in which crosslinks such as burette and allophanate are actively introduced into the yarn. In this case, depending on the degree of the cross-linking density, a behavior like II and III in the figure is exhibited, and the resistance to heat increases. However, the fact is that there is no heat-resistant yarn that behaves like IV, V, VI, VII in the figure.

<Problems to be solved by the invention> Accordingly, an object of the present invention is to provide an unprecedented heat-resistant urethane elastic yarn having a suitable crosslinking density by a melt spinning method.

<Means for Solving the Problems> That is, the polyurethane elastic yarn of the present invention can be used in a thermoplastic polyurethane having a hardness A in the range of 60 to 90 in hardness A according to Shore hardness measurement standard JIS K6801. 10 to 30% by weight of a polyisocyanate compound containing 3 to 3 isocyanate groups, based on the thermoplastic polyurethane, and a cross-linking reaction is performed. The yarn is melt-spun and dissolved in dimethyl sulfoxide to which a monoamine compound is added. It is characterized by having an insoluble portion of 2% by weight or more.

In a polyurethane elastic yarn obtained by a melt spinning method, a crosslink density, which is an important factor for imparting heat resistance, is determined by a chemical and physical method as is well known. First, as a chemical measurement method, journal
Of Polymer Science: Polymer Letters Edition, Vol. 17, pp. 175-180 (1979) [J. Polymer
Sci .: Polymer Letters Edition, Vol. 17, 175-180 (197
9)] and the method of Yokoyama et al. That is, this is a method in which a cross-linking bond is cleaved in dimethyl sulfoxide containing a monoamine such as propylamine, butylamine, hexylamine, and aniline, and excess monoamine is back-titrated with an acid. As a simple method, we decided to measure the weight of the insoluble portion in dimethylsulfoxide to which butylamine was added among the above monoamines after 24 hours at room temperature. As the n-butylamine concentration, 1/50 N was used in order to sufficiently break the cross-linking at room temperature. Further, as a physical measurement method of the crosslink density, a method such as a value IR from the Young's modulus, NMR, stress relaxation under heating, and creep can be considered, but we focused on creep measurement of temperature-elongation. We have already developed an apparatus and a method for measuring the amount of creep, that is, the amount of elongation in a non-contact manner.
Filed as -27103. Using this apparatus and method, yarns of various crosslink densities were prototyped and measured. Of course, the heat resistance of the yarn changes depending on the creep measurement conditions. That is, the load on the sample is usually 1 mg / d, but in the case of such a light load, it often does not match the actual situation in the actual processing step. This is considered to be due to the fact that an external force is always applied to the yarn in the actual processing step.
Regarding the rate of temperature rise, in the actual processing step, particularly when considering the heat-moisture setting and the like, there are few cases where the temperature is used under a slow condition of, for example, 10 ° C./min. Therefore, as a result of intensive studies, we decided to use the conditions of a load of 12.5 mg / d and a heating rate of 70 ° C./min.

As a result of a detailed study based on the above measurement of the chemical and physical crosslink densities, it has been found that the following requirements are indispensable for providing industrially advantageous and suitable heat resistance. That is, (1) When dissolved in dimethyl sulfoxide to which a monoamine compound is added, it is essential that there is an insoluble portion of 2% by weight or more. From another viewpoint, (2) temperature (T), elongation (ε) (ε = ΔL / L ₀ : ΔL =
Elongation, L ₀ = original length), from 80 ° C
In the region of 170 ° C, there is a portion where ∂ε / ∂T is 0 or / and a negative value, or (3) In the creep curve of temperature (T) and elongation (ε), ∂ / ∂T> 0 in the region and the variation (Δε) of the elongation (ε) is 3% or less. (4) In the creep curve of the temperature (T) and the elongation (ε), It is essential to have a portion where the value of elongation (ε) is negative in the region of 190 ° C.

As a method for producing a yarn having a suitable crosslinking density as described above, for example, a method in which a polyisocyanate compound is melt-mixed with a thermoplastic polyurethane elastic body during melt spinning and spinning can be suitably used. The polyisocyanate compound to be used is a compound having two or more isocyanate groups in the molecule, and more preferably a prepolymer having a functionality of 2 to 3 of the isocyanate group. That is, as the isocyanate component constituting the polyisocyanate compound, p, p'-diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TD
I), bifunctional isocyanates such as hexamethylene diisocyanate, or adducts of these diisocyanates with low molecular weight polyols such as trimethylolpropane and hexanetriol (trifunctional or higher isocyanates) or diisocyanates and the above trifunctional or higher functional isocyanates. A mixture with isocyanate, or crude MDI,
Crude TDI and the like. On the other hand, examples of the polyol component include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, propylene oxide and / or polyether diol or triol to which ethylene oxide and / or butylene oxide are added. Polycaprolactone diols, polycarbonate diols, polyester diols such as polybutylene adipate, or lactones of ε-caprolactone mixed with triol, tetrol, pentol, hexol and glycol, or polycaprolactone polyols polyadded to the above polyols Is raised.

Further, as another example, condensed polyester polyols such as ethylene glycol, propylene glycol, diethylene glycol, low molecular weight diols such as butylene glycol, and trimethylolpropane, hexanetriol, triols such as glycerin and succinic acid, maleic acid, adipic acid Examples include a polycondensation reaction product with a dibasic acid.

As described above, the polyisocyanate compound used in the present invention is a reaction product comprising an isocyanate component and a polyol component, and the number of isocyanate groups contained in one molecule of the compound is from 2 to 3, preferably from 2.03 to 2.8. It is synthesized so that

If the number of the functional groups is too small, the heat resistance of the composite system decreases, while if it is too large, the viscosity becomes high and the handling becomes inconvenient. Further, the molecular weight of the polyisocyanate compound is preferably 400 or more, particularly preferably 800 to 5000. The isocyanate group content NCO% of the polyisocyanate compound is preferably in the range of 3 to 20%. The amount of the polyisocyanate compound varies depending on the NCO group content and the type of the polyisocyanate compound used.
A range from 10 to 30% by weight is preferred.

 On the other hand, thermoplastic polyurethane elastomer is mainly
Refers to polyurethane in a broad sense with urethane bonds,
Hard segment amount is Shore hardness measurement standard JIS
The hardness A according to K6801 is preferably in the range of about 60 to 90. this
If the hardness is too high, the resistance to heat will increase
However, the recovery from room temperature or under heating is markedly impaired.
What is called spandex Will not function as
It is not preferable. Conversely, if it is too low, spinning is uneasy
It is easy to be fixed. Being thermoplastic and having the above hardness
For example, urethanes with partial cross-linking even in linear polyurethane
Can also be used.

<Example> Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Example 1 Dehydrated polycaprolactone diol having a hydroxyl value of 57.3
1021.5 parts and 90.2 parts of 1,4-butanediol were charged into a kneader equipped with a jacket, sufficiently dissolved with stirring, and then maintained at a temperature of 85 ° C., and 388.4 parts of p, p′-diphenylmethane diisocyanate was added thereto. The reaction was performed to obtain a thermoplastic polyurethane. The obtained reaction product was taken out of the kneader, and this was formed into a pellet by an extruder. This molded product has a relative viscosity in dimethylformamide at 25 ° C.
2.19.

The molded product had a Shore hardness A of 80. Using a similar composition and method, a polymer having a hardness of 90 and a relative viscosity of 2.25 was obtained.

The polyisocyanate compound A, B or C shown in Table 1 was injected and mixed into the above-mentioned polyurethane melted by a supply device, and the mixture was spun into a nozzle having a diameter of 0.5 mm, and spun at a speed of 600 m / m.
A 40d filament was obtained at a speed of minutes. The results are shown in Table 2.

In this table, the recovery rate at 190 ° C. is a recovery rate when a sample yarn stretched by 30% is heat-treated at 190 ° C. for 1 minute with dry heat, and is a value calculated by the following equation.

L ₀ : Length of sample yarn (mm) L: Length of sample length L ₀ extended by 30% (1.3 L ₀ mm) L ': Yarn length when relaxed at room temperature after subjecting sample yarn to tension dry heat treatment Weight (mm) The degree of crosslinking means the weight (m) of the sample insoluble matter after immersing the sample yarn in 1/50 N n-butylamine-dimethylsulfoxide at room temperature for 24 hours and the weight of the sample before immersion in the above solution (M ₀ ). That is, Is required.

From Table 2, figure I, II, III of creep curve (Comparative Example 1)
Yarns such as -1,1-2,1-4) have a low degree of crosslinking and a temperature of 190 ° C.
It can be seen that the recovery rate shows only a very small value. On the other hand, it can be seen that the yarn of the present invention has a higher degree of cross-linking as the amount of the polyisocyanate compound added increases, and that the degree of cross-linking is much higher than that of the comparative example, so that the heat resistance is also higher.

<Effect of the Invention> Since the yarn obtained by the present invention is based on the melt spinning method,
It is extremely advantageous as an industrial production method as compared with other spinning methods (for example, dry spinning method). Furthermore, since it is excellent in heat resistance, it can be applied to various uses, for example, socks, swimsuits, foundations and the like, in particular, fields requiring heat resistance.

[Brief description of the drawings]

FIG. 1 is a creep curve of the temperature-elongation of various polyurethane-based elastic yarns. In the figure, I to III are conventionally known, and IV to VII are those of the heat-resistant polyurethane elastic yarn of the present invention.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) D05B 1/00-83/00

Claims (2)

(57) [Claims] 1. A thermoplastic polyurethane having a hardness A in the range of 60 to 90 in hardness A according to Shore hardness measurement standard JIS K6801 is mixed with a polyisocyanate compound containing 2 to 3 isocyanate groups in one molecule. This is a yarn obtained by melt-spinning a polymer crosslinked by adding and reacting 10 to 30% by weight based on a plastic polyurethane and having an insoluble portion of 2% by weight or more when dissolved in dimethyl sulfoxide to which a monoamine compound is added. , Temperature (T), elongation (ε)
In the creep curve of (1), there is a portion where ∂ε / ∂T is 0 or / and a negative value in the region of 80 ° C to 170 ° C, and (2) ∂ε / ∂T in the region of 110 ° C to 160 ° C. ΔT> 0, and the variation (Δε) of the elongation (ε) is 3% or less, and (3) a portion where the value of the elongation (ε) is negative in a region from room temperature to 190 ° C. A polyurethane elastic yarn characterized by satisfying any one of the following. 2. The polyurethane elastic yarn according to claim 1, wherein the polyisocyanate compound contains 2.03 to 2.8 isocyanate groups in one molecule.