JP2869209B2 - Composite elastic yarn - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite elastic yarn comprising a polymer comprising ethylene and an ethylenically unsaturated monomer (hereinafter referred to as an ethylene copolymer) and a crosslinked polyurethane.

[0002]

2. Description of the Related Art Polyurethane elastic yarns are mainly produced by a dry spinning method, a wet spinning method and a melt spinning method. Among them, the melt spinning method does not require the use of a solvent, has a high spinning speed, and is advantageous as an industrial production method.

[0003] On the other hand, however, this yarn has a drawback that it has a rubbery feel and is easily blocked. For this reason, improvements such as addition of a release agent to an oil agent or a polymer have been made.

Further, a composite elastic yarn having a polyolefin sheath and a thermoplastic polyurethane core has been proposed (for example, JP-A-61-194221). As another method for preventing sticking, Japanese Patent Publication No. 14245/1986 proposes a method for producing a core-sheath type polyurethane-based elastic yarn in which urethane is provided in a sheath and crosslinked polyurethane is provided in a core.

[0005]

Among them, the improvement from the oil agent has a certain effect but is not complete but has a limit. That is, considering the case of spinning and winding, if the sticking of the yarn is reduced, it is likely that winding for a long time becomes impossible due to twill drop, winding collapse and the like. This tendency increases as the winding speed increases (for example, 500
m / min or more), and becomes remarkable as the diameter of the bobbin at the time of winding becomes smaller (for example, 100 mm or less in diameter). Conversely, if glue is applied to the yarn, it will be possible to take up the yarn for a long time, but it will not be possible to unwind the yarn in a later step, causing a serious trouble. As described above, it is often impossible to respond only by delicate control of the oil agent. In addition, many of the oils must be mainly composed of silicon, which may cause a problem in a subsequent process.

On the other hand, when the urethane-urethane-type core-sheath composite elastic yarn is used to eliminate sticking, there is a difficulty in high-speed and long-time winding with a small-diameter bobbin during spinning. There was also a problem in heat resistance.

Next, the yarn described in JP-A-61-194221 in which a polyolefin sheath is used as a core-sheath composite spin is extremely poor in heat resistance, and its use is limited. When polyurethane having a high melting point is used for the core in order to increase the heat resistance, there is a problem in that the obtained composite yarn has poor recoverability.

On the other hand, ethylene copolymers have excellent properties such as cold resistance, light resistance, chemical resistance, light weight, and non-toxicity.
It is used for various applications. However, since these materials alone have poor mechanical properties and thermal properties, most of the fibers are mainly used for adhesion.

[0009] It is an object of the present invention to provide a novel heat-resistant composite elastic yarn in which the adhesive property unique to polyurethane elastic yarn is improved. Another object is to provide a composite elastic yarn which can be produced stably and industrially advantageously by a melt spinning method.

[0010]

Means for Solving the Problems In view of the present situation, the present inventors have made intensive studies to achieve the above object, and as a result, have reached the present invention.

That is, the composite elastic yarn of the present invention is a core-sheath type composite elastic filament comprising polyurethane as a core component and a polymer comprising ethylene and an ethylenically unsaturated monomer as a sheath component. The composite ratio (X) of 3 to 10
0, the polyurethane is crosslinked with a crosslinking density (Y) of 10 (μmol / g) or more, and X and Y satisfy the following formula: Y ≧ −X + 30.

The above-mentioned crosslinks of the polyurethane are formed by allophanate bonds mainly due to the polyisocyanate contained therein. The polyisocyanate contained in the polyurethane enhances the mutual adhesion between the core component and the sheath component. The core component may be arranged eccentrically in the sheath component, but concentric arrangement is most preferred.

Hereinafter, the present invention will be described in detail. The crosslinked polyurethane of the core component constituting the present invention is not a normal thermoplastic polyurethane but a crosslinked polyurethane mainly having an allophanate crosslinked structure introduced therein.
As a method of making such a crosslinked polyurethane,
A method in which a polyisocyanate and a molten thermoplastic polyurethane are reacted during or after spinning to form an allophanate crosslinked structure mainly in the molecule, for example, a method proposed by us (Japanese Patent Publication No. 58-4657).
No. 3).

Here, the thermoplastic polyurethane refers to a polyurethane in a broad sense having a urethane bond or a urea bond in a molecule. As long as it is thermoplastic, it is possible to use either a flocculent urethane or a urethane having a partially cross-linked bond.

[0015] The hardness of the thermoplastic polyurethane is preferably in the range of 60 to 95 according to JIS-A. Hardness is 60
If it is less than this, problems such as poor recovery of the obtained yarn and poor heat resistance occur, which is not preferable. Conversely, if the hardness is more than 95, the recoverability of the polyurethane itself is inferior, and problems such as a narrow range of optimum spinning conditions of the polyurethane having the hardness are not preferable. Therefore, 65-92
Is most preferable.

The polyisocyanate used in the present invention generally has a molecular weight of 300 or more, preferably 400 or more.
More preferably, a reaction product of a polyfunctional polyol having a bifunctional to trifunctional hydroxyl group of 800 to 5000 and a polyfunctional isocyanate (for example, diphenylmethane diisocyanate, trifunctional isocyanate, or a mixture thereof) can be exemplified. The functionality of the polyisocyanate is such that the polyol component has an average functionality of 2.0.
It is preferable to use those having a range of from 5 to 2.8 and the polyfunctional isocyanate component having a range of from 2.0 to 2.8. When the polyol component has an average functionality of only 2.0, it is desirable that free isocyanate groups be present in the polyisocyanate. For example, the ratio R of the number of moles of isocyanate groups / the number of moles of hydroxyl groups is 2 0.0 or more. Further, when R is 2.1 to 5, the heat resistance of the core component is improved, which is advantageous. If R is less than 2.1, it is not preferable from the viewpoint of heat resistance, while if it exceeds 5, it is not preferable from the viewpoint of operability.

The amount of the polyisocyanate in the core component is preferably 5 to 40% by weight based on the mixture of the thermoplastic polyurethane and the polyisocyanate to be spun. The addition amount varies depending on the type of the polyisocyanate used. However, if the addition amount exceeds 40% by weight, the mixing becomes uneven and the spinning becomes unstable, and the mechanical properties of the yarn are unsatisfactory. , On the contrary, 5% by weight
If it is less than this, heat resistance will be insufficient, which is not preferable.

As described above, the core component having the crosslinking density (Y) of the present invention can be obtained. It is preferred that the crosslinks consist primarily of allophanate crosslinks.
That is, if the cross-linking is a burette bond, the viscosity of the system increases during spinning, and stable operation cannot be expected.

The cross-link density (Y) referred to in the present invention is the cross-link density of urethane in the core component. As a measuring method, first, urethane after dissolving the sheath component with xylene, toluene or the like is used. . Then, the method of Yokoyama et al. (Journal of Polymer Science: Polymer Letters Edition; vol. 17, p. 175 (1979)) and "Journal of the Rubber Society of Japan" Vol. 61, No. 6, P430
(1988) with reference to the Murakami method. That is, 1 g of this urethane is first placed in a dimethyl sulfoxide-methanol mixed solution at 23 ° C. for 12 hours and stirred, and then dissolved in a dimethyl sulfoxide solution containing about 200 μmol / g of n-butylamine at 23 ° C. for 24 hours. After that, n-butylamine in the reaction system was back titrated with a 1/50 to 1 / 125N hydrochloric acid-methanol solution using bromophenol blue as an indicator, and the density was determined by the following equation.

V ₀₁ = V ₀ × W ₂ / W ₁ W ₁ : Weight of decomposed liquid in sample decomposition (g) W ₂ : Weight of prepared decomposition liquid in sample decomposition (g) V ₀ : Titration required for blank test (ml) V ₀₁ : Empty test titer in sample decomposition (ml) ) V _S : titration amount in sample decomposition (ml) f _HC1 : titer (−) N _HC1 : titrant concentration (normative)

In this method, a core component having a high cross-linking density that does not dissolve the sample can be considered.
Such a system can be suitably used as long as the spinnability is good. In particular, when the hardness of the sheath component is high and the elongation recoverability at room temperature is inferior, the core component needs to express a resilience that overcomes the rigidity of the sheath component.
mol / g or more, preferably 20 μmol / g or more, more preferably 25 μmol / g or more.

The ethylene copolymer used for the sheath component in the present invention refers to a thermoplastic copolymer obtained by copolymerizing ethylene with an ethylenically unsaturated monomer which can be added to the ethylene copolymer. Examples of the ethylenically unsaturated monomer include vinyl acetate or its complete or incomplete saponified product, or acrylic acid or its alkyl ester, or methacrylic acid or its alkyl ester. Examples of the former are ethylene-vinyl acetate copolymers, saponified ethylene-vinyl acetate copolymers (eg, ethylene vinyl alcohol copolymer in the case of completely saponified products), and examples of the latter are ethylene acrylic acid copolymers , Ethylene ethyl acrylate copolymer, ethylene methacrylic acid copolymer,
Ethylene ethyl methacrylate copolymer is mentioned.

Among the above-mentioned ethylenically unsaturated monomers, vinyl alcohol and acrylic acid having a hydroxyl group, a carboxyl group and the like reactive with an isocyanate group in the molecule are particularly preferable. Examples of such ethylene copolymers include “Evaflex” (manufactured by DuPont-Mitsui Polychemicals), “Smitate” (manufactured by Sumitomo Chemical Co., Ltd.),
"Ultracene", "Mersen" (Toyo Soda Kogyo Co., Ltd.), "Dumilan D or C" (Takeda Pharmaceutical Co., Ltd.), "NUC copolymer" (Nippon Unicar Co., Ltd.),
Commercially available products such as "EVAL" (manufactured by Kuraray Co., Ltd.) can be suitably used.

Having described both the core and sheath components, the composite ratio of the core and sheath will now be described. The composite ratio of the core / sheath component is in the range of 3 to 100 in terms of cross-sectional area ratio, preferably 10
~ 70, more preferably 20 ~ 50. When the ratio of the sheath component is less than 3, the elastic recovery of the obtained yarn, the recoverability at high temperature, and the heat resistance are insufficient, and when the ratio exceeds 100, the sheath component is broken or the core component is a yarn. It is not preferable because it is easily exposed on the surface and adversely affects spinnability and the like.

In order to have a sufficient function as a composite yarn, not only the above-mentioned composite ratio but also the crosslink density of polyurethane in the core component is important for the present invention. Between this crosslinking density Y (μmol / g),
The crosslink density of Y must be 10 or more, and the relational expression of Y ≧ −X + 30 must always be established. That is, when the crosslink density of the polyurethane in the core component is low, it is necessary to increase the ratio of the core component according to the above formula. Conversely, when the crosslink density of the polyurethane in the core component is high, the composite ratio is high. Can expand the scope of application. Yarns that are configured not to satisfy this equation are:
It is not preferable because the function as a composite yarn, for example, recoverability and heat resistance are inferior.

As the composite form of the core and the sheath, it is preferable that the centers of both components of the core and the sheath are substantially the same from the viewpoint of spinning stability and the uniformity of the obtained yarn. The cross-sectional shape of the composite yarn may be circular or irregular.

The core component and the sheath component of the present invention include known light-resistant agents, antioxidants, dyes and pigments such as titanium oxide, lubricants and antibacterial agents, conductive agents, antistatic agents, flame retardants, and other known polyurethanes and ethylene copolymers. It is also possible to add modifiers.

Next, the apparatus and method for producing the yarn of the present invention will be described. A polyisocyanate is added to a portion where a thermoplastic polyurethane is melt-extruded, a portion where a polyisocyanate is mixed, a portion where a sheath component is melt-extruded, and a melt composite spinning apparatus equipped with a spinning head having a known core-sheath type composite spinneret. Is preferred. As a device used for adding the polyisocyanate during spinning, a known device can be used. It is possible to use a kneading device having a rotating portion in the portion where the polyisocyanate is added to and mixed with the polyurethane in a molten state, but it is more preferable to use a mixing device having a stationary kneading element. is there. As a mixing apparatus having a stationary kneading element, a known mixer, for example, a static mixer manufactured by Kenix Corporation can be used. The shape and the number of elements of the static kneading element are different depending on the conditions to be used, but the thermoplastic polyurethane elastic body and the polyisocyanate are sufficiently mixed before being discharged from the composite spinneret. It is important to select, usually 20 to
90 elements are provided. The polyurethane mixed with the polyisocyanate is used as a core component, the sheath component is melted by another extruder, and both are guided to a core-sheath composite die and spun to obtain the composite yarn of the present invention.

When the core / sheath composite ratio X is increased to, for example, 15 or more, the structure of the junction between the core component and the sheath component in the design of the core-sheath composite die is determined by: For example, 2.0 mm or less. (B) The distance between the lower part of the core component introduction hole (internal orifice) and the upper part of the core-sheath composite flow discharge hole (final orifice) is, for example, 0.05 to
It is preferable to take measures such as reducing the size to 1.0 mm.

The thermoplastic polyurethane pellets are supplied from a hopper and are heated and melted by an extruder. Melting temperature is 19
A range from 0 to 230 ° C is preferred. On the other hand, the polyisocyanate melts at a temperature of 100 ° C. or less in the supply tank,
Defoam beforehand. If the melting temperature is too high, the polyisocyanate is liable to be degraded. Therefore, the melting temperature is preferably as low as possible, and a temperature between room temperature and 100 ° C. is appropriately used. The melted polyisocyanate is measured by a metering pump, filtered if necessary with a filter, and added to the melted polyurethane at an association section provided at the extruder tip. The polyisocyanate and the polyurethane are kneaded by a kneading apparatus having a static kneading element. This mixture is metered by a metering pump and introduced into the spinning head. It is preferable that the spinning head is designed to have a shape in which the mixture stays as little as possible. After removing foreign matter with a filter medium such as a wire mesh or glass beads in a filtration layer provided in the spinning head as necessary, the mixture is combined with the ethylene copolymer of the sheath component in a core-sheath type, and then discharged from the die, It is air-cooled and wound up after the oil agent is applied. The winding speed is usually 400 to 1500 m / min.

The composite elastic yarn wound up on the spinning bobbin is
Although the strength may be inferior immediately after spinning, the strength improves during standing at room temperature (for example, 2 hours to 6 days). The yarn quality and thermal performance of the composite elastic yarn thus spun change with time because the reaction with the polyisocyanate mixed with the thermoplastic polyurethane used as the spinning raw material is not completed during spinning. In addition, it is presumed that it proceeds after spinning. Immediately after spinning, the adhesiveness of the core-sheath may become poor, but this adhesiveness will be improved over time. This is considered to be due to the reaction between the hydroxyl group, carboxyl group, etc. in the ethylene copolymer and the polyisocyanate.

[0032]

As described above, since the sheath component of the yarn of the present invention is an ethylene copolymer and the core component is a cross-linked polyurethane, the yarn handling properties are extremely high as well as thermal and mechanical properties. Good. Ethylene copolymers have a large temperature dependence of mechanical properties, and abrupt deterioration in physical properties occurs at about 50 to 60 ° C. At present, this phenomenon is a serious obstacle in practical use. The inventive yarns are also surprisingly very good in heat resistance. For example, when examining the creep behavior of elongation-temperature, the heating temperature was 70 ° C./min, and the load was 12 mg.
When the creep property of the yarn is measured under the condition of / d, the yarn of the present invention has an elongation at 40% of 130 ° C. or more, and is excellent in heat resistance. Further, although the strength of the ethylene copolymer alone is extremely low, the mechanical properties are surprisingly improved, for example, from about 0.1 g / d to about 1.5 g / d by the composite as in the present invention. Of course, there is no sticking between the fibers. Furthermore,
Since an aggressive reaction occurs at both core-sheath interfaces, their adhesion is good. Further, the productivity is also a melt spinning method, which is advantageous in industrial production. The composite elastic yarn of the present invention can be applied to the fields of socks, swimwear, foundation, brassiere and the like. Further, it can be used as a medical material by utilizing the non-toxicity of the sheath component.
Next, not only this yarn but also, for example, nylon or the like can be used for covering or tying.

[0033]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

Examples 1-3, Comparative Examples 1-3 Thermoplastic polyurethane 17 mol of polybutylene adipate having a number average molecular weight of 2,000 and p, p'-diphenylmethane diisocyanate 50
Mol and 1,4-butanediol 32 as a chain extender
The compound was synthesized according to a conventional method using a mole. Its relative viscosity was 2.15.

Polyisocyanate polycaprolactone diol 2 having a number average molecular weight of 850
4.1 mol, 6.0 mol of polycaprolactone triol having a number average molecular weight of 2,000 (average functionality of the polyol component = 2.2), and 69.9 mol of p, p'-diphenylmethane diisocyanate were reacted to obtain this compound. . Its NCO% was 6.2% by weight.

Ethylene copolymer-ethylene vinyl acetate copolymer Ultracene 682 (manufactured by Tosoh Corporation: melt flow rate 150 g / min, vinyl acetate content 15%; melting point: 8)
3 ° C.).

When the thermoplastic polyurethane is melted, the polyisocyanate is injected by a supply device, and both components are kneaded with a static mixer (manufactured by Kenix) having 35 elements of a static kneading element to form a core component. The vinyl acetate copolymer resin is melted by another extruder, weighed separately from each other, led to a concentric core-sheath composite die (nozzle diameter 0.5 mm), and fed to a bobbin with an outer diameter of 85 mm at a spinning speed of 600 m / min. A composite monofilament having a fineness of 40 denier was obtained. At this time, the ejection amount of both components and the amount of polyisocyanate were changed so as to obtain the composite ratio and the crosslinking density shown in Table 1.

The sheath component is similarly composite-spun using the above-mentioned thermoplastic polyurethane, and as an oil agent, an oil agent mainly composed of dimethylsilicone containing 5% by weight or 0.3% by weight of an amino-modified silicon of an isocyanate group deactivator. And wound up (Comparative Examples 1 and 2).

Table 1 shows the results.

[Table 1]

SRII: a value calculated by the following equation after repeating 100% elongation-relaxation twice at room temperature, and the larger the value, the better the recovery.

Heat resistance: When a load of 12.5 mg is applied to the yarn and measured at a heating rate of 70 ° C./min, it indicates the temperature at which the yarn is stretched by 50%.

Unwinding coefficient: When the urethane yarn wound on the bobbin is unwound at a speed of 50 m / min, the bobbin surface speed when the yarn cannot be released due to sticking of the bobbin surface and Ratio to the surface speed of the take-up roller.

Spinning property: Time required for winding without traversing and collapse.

From Table 1, it can be seen that the spinning take-up property is 24 minutes when sticking is eliminated as in Comparative Example 1 of the urethane-urethane type, while the sticking property is good when sticking is performed as in Comparative Example 2. Nevertheless, this yarn could not be used unless it was wrapped. Also, as in Comparative Examples 3 and 4, the crosslinking density Y (μmol /
g) does not satisfy Y ≧ −X + 30, recoverability,
It turns out that heat resistance is significantly inferior.

On the other hand, in the first and second embodiments satisfying this equation,
It can be seen that the physical properties are not inferior to the urethane-urethane type composite, and that there is no sticking and the spinning property is excellent. Further, it can be seen that when the crosslinking density of the core component is increased as in Example 3, the heat resistance is significantly improved.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-61-194221 (JP, A) JP-A-1-118619 (JP, A) JP-B-61-14245 (JP, B2) International publication 91/5088 (WO, A1) (58) Field surveyed (Int. Cl. ⁶ , DB name) D01F 8/16 D01F 8/10

Claims (3)

(57) [Claims] 1. A core / sheath composite elastic filament comprising polyurethane as a core component and a polymer comprising ethylene and an ethylenically unsaturated monomer as a sheath component, wherein the core / sheath composite ratio (X) is 3 ~ 100, polyurethane is 1
A composite elastic yarn which is crosslinked with a crosslinking density (Y) of 0 (μmol / g) or more, and wherein X and Y satisfy the following formula: Y ≧ −X + 30. 2. The composite elastic yarn according to claim 1, wherein the crosslinking is allophanate crosslinking by a polyisocyanate. 3. The composite elastic yarn according to claim 1, wherein the ethylenically unsaturated monomer is vinyl acetate or its completely or partially saponified product, acrylic acid or its alkyl ester, or methacrylic acid or its alkyl ester. .