JPH03213515A - Heat-resistant polyurethane elastic yarn - Google Patents

Abstract

PURPOSE:To obtain the subject yarn which is yarn crosslinked by reaction of a thermoplastic polyurethane with a polyisocyanate compound, having specific physical properties, excellent in heat resistance due to a moderate crosslinking density and producible by an industrially advantageous melt spinning method. CONSTITUTION:The objective yarn which is polyurethane elastic yarn, crosslinked by reaction of (A) a thermoplastic polyurethane with (B) a polyisocyanate compound and containing >=2wt.% undissolved part present in dissolving the yarn in dimethyl sulfoxide containing a monoamine compound added thereto. The aforementioned yarn is preferably obtained by melt mixing the component (B) with an elastomer of the component (A) in melt spinning and spinning the resultant mixture. A polyisocyanate prepared by reacting an NCO component such as tolylene diisocyanate with a polyol component such as polyether diol and having 2.03-2.8 number of NCO groups and 800-5000 molecular weight is preferred as the component (B).

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 with excellent heat resistance obtained by a melt spinning method.

<Prior Art> It is known that the heat resistance of polyurethane elastic yarn, so-called spandex 0, is greatly affected by its manufacturing method, such as dry, wet, or melt spinning. Among these, in the yarns obtained by dry and wet spinning, diamine is used as a chain extender so that the hard segment domains can form strong hydrogen bonds, and as a result, the heat resistance of the yarns is improved. On the other hand, in the yarn obtained by the melt spinning method, strong hard segments are not generated because the thermoplastic polyurethane is melted once, and the heat resistance such as recovery ability and resistance from high temperatures is significantly lower than that of the yarn obtained by the above two spinning methods. is inferior to.

If we consider the temperature-elongation creep curve as a measure of heat resistance, yarns with no heat resistance creep at low temperatures, that is, the amount of elongation increases rapidly, and yarns with heat resistance creep at high temperatures. Does not creep into the area. If we focus on this creep behavior, a yarn made by melt-spinning thermoplastic polyurethane as it is will exhibit creep behavior as shown in ■ in Figure 1, but a yarn made by actively introducing cross-linking such as billet or allophanate into the system Depending on the size of the crosslinking density, the material exhibits the behavior shown in (■) and (■) in the figure, and its resistance to heat increases. However, the reality is that there is still no heat-resistant yarn that behaves as indicated by IV and VVI■ in the figure.

<Problems to be Solved by the Invention> Therefore, the present invention is to provide an unprecedented heat-resistant urethane elastic yarn having a suitable crosslinking density using a melt spinning method.

Means for Solving the Problems> That is, the polyurethane elastic yarn of the present invention is a yarn crosslinked by the reaction of thermoplastic polyurethane and a polyisocyanate compound, and when dissolved in dimethyl sulfoxide to which a monoamine compound has been added, 2 It is characterized by having an undissolved portion of at least % by weight.

The crosslinking density, which is an important factor in imparting heat resistance to polyurethane elastic yarns obtained by melt spinning, is determined by chemical and physical methods, as is well known. First, as a chemical measurement method, see Journal of Polymer Science: Polymer Letters Edition, Vol. 17, pp. 175-180 (1979) (J, Polymer Sci,: Polymer Sci.
mer Letters Edition, Vol.
The method of Yokotoba et al. by amine decomposition described in IL 175180 (1979)) is mentioned. That is, the method involves cleaving crosslinks in dimethyl sulfoxide containing monoamines such as propylamine, butylamine, hexylamine, aniline, etc., and then back titrating excess monoamines with acid. As a simple method, we decided to measure the weight of the insoluble portion of the monoamine after 24 hours at room temperature in dimethyl sulfoxide to which butylamine was added. The n-butylamine concentration was 1150 to sufficiently cleave crosslinks at room temperature.
N was used. Further, as a physical method for measuring the crosslink density, methods such as IR, NMR, stress relaxation under heating, and creep based on Young's modulus can be considered, but we focused on temperature-elongation creep measurement. We have already filed an application for an apparatus and method for non-contact measurement of the amount of creep, that is, the amount of elongation, in Japanese Patent Application No. 1-27103.

Using this device and method, we prototyped yarns with various crosslinking densities,
It was 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 I mg/
d is used, but in the case of such a light load, it often does not suit the actual situation in the actual machining process. this is,
This is thought to be because in the actual processing process, external forces are often applied to the yarn. Also, regarding the temperature increase rate, in actual processing steps, especially when considering heating settings, there are not many cases in which a slow temperature increase rate of 10° C./min is used, for example. After careful consideration, we decided on 12.5m.
It was decided to use the conditions of a 5-g/d load and a temperature increase rate of 70° C./min.

As a result of detailed study based on the above chemical and physical crosslink density measurements, it was found that the following requirements are essential in order to provide 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. Also, from another point of view, (2) Temperature (T), elongation rate (ε) (ε-ΔL/LO:Δ
In the creep curve of I, - elongation, L, - original length,
In the region from 80'C to 170'C, there is a part where ε/, JT is O or/and a negative value, or (3) in the creep curve of temperature (T) and elongation rate (ε), 110 'Dε1 T〉0 in the area from 'C to 160℃,
In addition, the amount of change (Δε) in the elongation rate (ε) is 3% or less, or (4) In the creep curve of temperature (T) and elongation rate (ε), the elongation rate (ε) in the region from room temperature to 190℃ ) must have a negative part.

As a method for producing a yarn having a suitable crosslinking density as described above, for example, a method of melt-mixing a polyisocyanate compound with a thermoplastic polyurethane elastomer during melt spinning and spinning the mixture can be suitably used.

The polyisocyanate compound used is a compound having two or more isocyanate groups in the molecule,
More preferably, a prepolymer having an isocyanate group functionality of 2 to 3 is suitable.

That is, as the isocyanate component constituting the polyisocyanate compound, p,p'-diphenylmethane diisocyanate (MDI), tolylene diisocyanate (
TDI), bifunctional isocyanates such as hexamethylene diisocyanate, or adducts of these diisocyanates with low molecular weight polyols such as trimethylolpropane, hexanetriol, etc. (tri- or higher-functional isocyanates), or diisocyanates and the above-mentioned tri- or higher-functional systems. isocyanate, crude MDI, crude TDI, etc.

On the other hand, examples of the polyol component include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, propylene oxide, and/or polyether diols or triols to which ethylene oxide and/or butylene oxide are added. Furthermore, polyester diols such as polycaprolactone diol, polycarbonate diol, and polybutylene adipate, or mixtures of ε-caprolactone lactone with triol, tetrol, bentol, hexol, and glycol, or polycaprolactone polyols obtained by polyaddition to the above polyols. can be given.

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

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

If the number of functional groups is too small, the heat resistance of the composite yarn will decrease, and if it is too large, the viscosity will increase, making handling difficult, which is not preferable. In addition, the molecular weight of the polyisocyanate compound is 400 or more, especially 800 to 5000.
is preferred. Further, the isocyanate group content NCO% of the polyisocyanate compound is preferably in the range of 3 to 20%. The amount of the polyisocyanate compound added varies depending on the NCO group content and type of the polyisocyanate compound used, but is preferably in the range of 5 to 40% by weight, particularly preferably The ratio is 10 to 30%.

On the other hand, thermoplastic polyurethane elastomer refers to polyurethane in a broad sense that mainly has urethane bonds in its molecules, and the amount of hard segments is determined according to the Shore hardness measurement standard JIS.
A hardness A according to K6801 is preferably in the range of about 60 to 90. If the hardness becomes too high, the resistance to heat will increase, but the recovery properties from room temperature or heating will be significantly impaired, and the material will no longer function as so-called spandex (2), which is not preferable. On the other hand, if it is too low, spinning tends to become unstable. As long as it is thermoplastic and has the above-mentioned hardness, linear polyurethane or urethane partially crosslinked can be used.

<Examples> The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 1021.5 parts of dehydrated polycaprolactone diol with a hydroxyl value of 57.3 and 90.2 parts of 1,4-butanediol
P and p' were charged in a jacketed Nigu, and after sufficiently dissolving with stirring, the temperature was kept at 85°C, and p, p'
-388.4 parts of diphenylmethane diisocyanate 0 was added and reacted. The obtained reaction product is
The mixture was taken out from the kneader and molded into pellets using an extruder. This molded product had a relative viscosity of 2.19 in dimethylformamide at 25°C.

The hardness of this molded body was 80. A polymer having a hardness of 90 and a relative viscosity of 2.25 was obtained using the same composition and method.

The polyisocyanate compounds shown in Table 1 were injected and mixed into the above melted polyurethane using a feeding device, and the polyisocyanate compounds shown in Table 1 were injected and mixed into the melted polyurethane.
The filament was guided through a 5 mm nozzle and spun to obtain a 40 d filament at a spinning speed of 600 m/min.

The results are shown in Table 2.

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

Lo: Sample thread length (mm) L: Sample length. The length obtained by elongating by 30% (1.3L, m
m) 1,': Thread length (mm) when the sample thread is relaxed at room temperature after tension dry heat treatment; degree of crosslinking is 1150
It is the value obtained by dividing the weight of undissolved matter (m) of the sample after immersing the sample system in N n butylamine-dimethyl sulfoxide at room temperature for 24 hours by the weight of the sample before immersing in the solution (mo). That is, it is determined by: Degree of crosslinking (%) = X 100 (%)O.

From Table 2, figure number 1 of the creep curve. II, I
It can be seen that yarns such as (Comparative Example 1-1.1-2.1-4) have a small degree of crosslinking and a very small recovery rate at 190°C. On the other hand, it can be seen that the degree of crosslinking of the yarn of the present invention increases as the amount of polyisocyanate compound added increases, and that the degree of crosslinking is much higher than that of the comparative example, and therefore, the heat resistance is also increased.

<Effects of the Invention> Since the yarn obtained by the present invention is produced by the melt spinning method, it is extremely advantageous as an industrial manufacturing method compared to other spinning methods (for example, dry spinning method). Furthermore, since it has excellent heat resistance, it can be applied to various uses, such as socks, swimwear, foundations, and other fields where heat resistance is particularly required.

[Brief explanation of drawings]

FIG. 1 shows creep curves of temperature elongation of various polyurethane elastic yarns, where I to ■ are conventionally known ones, and ■ to ■ are those of the heat-resistant polyurethane elastic yarns of the present invention.

Claims (1)

[Claims] 1. In a yarn crosslinked by the reaction of a thermoplastic polyurethane and a polyisocyanate compound, when dissolved in dimethyl sulfoxide to which a monoamine compound has been added, 2.
A polyurethane elastic yarn characterized by having an insoluble portion of at least % by weight. 2. Polyurethane elasticity characterized by having a portion where ∂ε/∂T is 0 or/and a negative value in the region from 80°C to 170°C in the creep curve of temperature (T) and elongation rate (ε) thread. 3. In the creep curve of temperature (T) and elongation rate (ε), ∂ε/∂T in the region from 110℃ to 160℃
>0, and the amount of change (Δε) in elongation rate (ε) is 3% or less. 4. A polyurethane elastic yarn characterized in that, in a creep curve of temperature (T) and elongation rate (ε), there is a portion where the elongation rate (ε) value is negative in the region from room temperature to 190°C.