JPH02160920A - Production of heat-resistant urethane yarn - Google Patents

Abstract

PURPOSE:To obtain a urethane yarn excellent in heat resistance by adding a specific prepolymer compound polymerized from a bifunctional polyol and diisocyanate components to a molten polyurethane and spinning the resultant mixture. CONSTITUTION:A prepolymer compound polymerized from a bifunctional polyol component (e.g. polytetramethylene glycol, having 800-2000 molecular weight) and a diisocyanate component (preferably diphenylmethane diisocyanate) at a molar ratio of NCO groups in the diisocyanate component to OH groups in the polyol component within the range of 2-4 is added and mixed with a molten polyurethane. The resultant mixture is then melt spun to afford the objective urethane yarn.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyurethane elastic yarn, and more particularly to a method G for producing a polyurethane elastic yarn with reduced heat resistance by a melt spinning method.

[Conventional technology]

There are three methods for producing polyurethane elastomers, which are broadly classified based on the spinning power tfx: dry spinning, wet spinning, and melt a-spinning. Among these, the melt spinning method does not require the use of solvents,
It also has advantages such as high spinning speed and compatibility of equipment, and is advantageous as an industrial manufacturing method.

However, polyurethane elastomers obtained by melt-spinning methods use thermoplastic polyurethane that can be melt-spun, and therefore have problems such as poor heat resistance and insufficient recovery from deformation at high temperatures.

The following methods have been proposed to solve this problem.

(1) Method of adding polyfunctional compounds to polymerization, etc. (2)
) A method of directly spinning from a polymerization system (3) A method of melt-spinning a semi-hardened polymer and extruding it into an isocyanate fixed temperature or a curing agent (4) A method of performing heat treatment after spinning [Problems to be solved by the invention] Among these methods, method (1) has the disadvantage that if sufficient crosslinking is applied to improve thermal stiffness, the melting temperature of the polymer increases, making it necessary to increase the spinning temperature and making the spinning unstable. be.

Regarding method (2), it is difficult to control the polymerization reaction, and there are problems such as retention and thermal stability during the process from the polymerized fiber to the spinning system.

Methods (3) and (4) are effective in terms of the heat resistance of urethane elastic threads and their recovery from deformation at high temperatures, but they require large processing equipment and are disadvantageous as they are expensive for industrial manufacturing methods. It can be said that

In addition, as a method for producing polyurethane elastic yarn with excellent heat resistance using the melt spinning method, we have developed
The method described in Publication No. 6573 has been submitted.

Therefore, as a result of intensive research on the method previously proposed, we surprisingly discovered a method for producing polyurethane elastic yarn with even better heat resistance.

An object of the present invention is to provide a method for producing urethane elastic yarn with excellent heat resistance using a melt spinning method. Another object is to provide a stable and industrially advantageous manufacturing method for such polyurethane elastic yarns.

[Failure to solve the problem]

The method for producing a heat-resistant urethane yarn of the present invention involves polymerizing a bifunctional polyol component and a diisocyanate-1 component when melting a thermoplastic polyurethane elastomer, and converting the diisocyanate-1 component to the OH group of the polyol component. N
It is characterized in that a prepolymer compound having a CO& molar ratio (RIt) in the range of 2 to 4 is added to and mixed with molten polyurethane, and then spun.

The bifunctional polyol component constituting the prepolymer compound of the present invention includes at least one member selected from the group consisting of polytetramethylene glycol, polypropylene glycol, polybutylene adipate diol, polycabralactone diol, and polycarbonate diol. Diols can be suitably used. This bifunctional molecular weight is 3
00-2500 is preferable, and 800-2000 is more preferable. If it is less than 300, the activity of the reactant with diisocyanate-1 is high, so that it tends to deteriorate during storage and is difficult to handle. On the other hand, if the molecular weight becomes too large, the amount of polyol component to be added increases when adjusting the R ratio to a predetermined value, which tends to make handling difficult.

Isocyanate components constituting the prepolymer compound include tolylene diisocyanate, diphenylmethane diisocyanate-1-,1,5-naphthalene diisocyanate, xylylene diisocyanate or modified products thereof, isobonron diisocyanate, water-added p, p'
-Diphenylmethane diisocyanate, etc. can be used. Diphenylmethane diisocyanate is preferred.

As a method for polymerizing a prepolymer from the above-mentioned polyol component and isocyanate component, a mixed polyol component is added to the molten isocyanate component and the isocyanate component is
so that the groups are in excess over the OH groups of the polyol component,
That is, the reaction may be carried out so that the R ratio is 2 to 4. At this time, if the viscosity of the system increases and defoaming becomes difficult,
A defoaming agent may be added to the system in advance.

The thermoplastic polyurethane elastomer used in the present invention contains a known segmented polyurethane copolymer, such as a polyol having a molecular weight of 500 to 6,000, such as dihydroxy polyether, dihydroxy polyester, and dihydroxy polylactone.

dihydroxy polyester amide, dihydroxy carbonate I, and their pro-2 copolymers, etc., and organic diisocyanates with a molecular weight of 500 or less, such as p, p'
-diphenylmethane diisocyanate, tolylene diisocyanate 1-, hydrogenated p,p diphenylmethane diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isoborone diisocyanate, 15-naphthylene diisocyanate, etc., and a chain extender such as water, hydrazine, diamine It is a polymer obtained by reaction with , glycol, etc.

Among these polymers, the polyols include polytetramethylene ether glycol or polycaprolactone polyester, polycarbonate diol, polyhexamethylene adipate, polybutylene adipate, polyneopentylene adipate, polyhexamethylene/butylene adipate copolymer diol, and polycarbonate. Polymers using a diol containing at least one selected from the group consisting of polyneopentylene/hexamethylene adipate copolymer diol and polyneopentylene/hexamethylene adipate copolymer diol are preferred. Moreover, p,p'-diphenylmethane diisocyanate is suitable as the organic diisocyanate. Further, as the chain extender, glycol is particularly suitable, and 14-bis(β-hydroxyethoxy)benzene and 1,4-butanediol are particularly suitable. As described above, in the present invention, as a thermoplastic polyurethane as a spinning raw material, a polymer synthesized without using a branching agent or a crosslinking agent is used in principle. Therefore, it is possible to maintain the spinning temperature at a low level, and thermal deterioration of polyurethane can be suppressed. Of course, polymers containing branching or crosslinking to the extent that the spinning temperature is not extremely high can also be suitably used.

The thermoplastic polyurethane used in the present invention can be synthesized using the so-called prepolymer method, in which a polyol and an organic diisocyanate compound are allowed to react and then reacted with a chain extender, or the so-called Wangshoso 1 method, in which all reaction raw materials are mixed at once. - Either law may be adopted. Although it is possible to use a solvent or diluent during polymer synthesis, bulk polymerization is more suitable for producing polymer pellets for solvent spinning. Preferred methods for bulk polymerization include a method of continuously or semi-continuously collecting the polymer using an extruder, or a method of obtaining a block, powder or flake polymer by hatching reaction.

In the present invention, in addition to fully thermoplastic polyurethane in which the polymer synthesis reaction has been sufficiently completed, which is used in the field of molded polyurethane elastomers, so-called incomplete thermoplastic elastomer, that is, with very few remaining isocyanate groups, is used. It is also possible to create crosslinking after molding using the pellets. However, such pellets have the problem of being susceptible to deterioration due to humidity, temperature, etc. during storage, so it is convenient to use thermoplastic polyurethane that has undergone a complete reaction.

The amount of the prepolymer compound of the present invention added is preferably 3 to 30% by weight, particularly preferably 5 to 20% by weight, based on the mixture of the thermoplastic polyurethane elastomer and the prepolymer compound to be subjected to spinning. The amount added varies depending on the type of polyisocyanate compound used, but if the amount added is small, the desired improvement in the thermal performance of the urethane thread will be insufficient. Moreover, if the amount added is too large, non-uniform mixing and a ring of decreased yarn quality tend to occur, making spinning unstable, which is not preferable.

The melt spinning of the present invention is preferably carried out using a spinning device equipped with a section for melt-extruding the thermoplastic polyurethane elastomer, a section for adding and mixing the prepolymer compound, and a spinning head. As such a spinning device,
Known equipment used for adding modifiers during spinning can be used. Although it is possible to use a kneading device having a rotating part for adding and mixing the prepolymer compound to the molten polyurethane, it is more preferable to use a mixing device having a stationary kneading element. be. A known mixing device having a static kneading element can be used. The shape and number of elements of the static kneading element vary depending on the conditions of use, but are selected so that sufficient mixing of the polyurethane elastomer and prepolymer compound is completed before they are discharged from the spinneret. Usually, 20 to 90 elements are provided.

An example of an embodiment of the present invention will be described below. Pellets of thermoplastic polyurethane elastomer are supplied from a hopper and heated and melted by an extruder. The melting temperature is preferably in the range of 190 to 230°C. On the other hand, the prepolymer compound is melted at a temperature of 100° C. or lower in a supply tank and degassed in advance. If the melting temperature is too high, the quality of the prepolymer compound is likely to change, so it is desirable that it is as low as possible within the melting range, and a temperature between room temperature and 100° C. is appropriately used. Measuring the molten prepolymer compound using a metering pump,
If necessary, it is filtered through a filter and added to the molten polyurethane at a meeting point provided at the tip of the extruder. The prepolymer compound and polyurethane are kneaded using a kneading device having stationary elements. This mixture is metered by a metering pump and introduced into the spinning head. As the spinning head, a conventional synthetic fiber spinning device may be used, but it is preferable to design the spinning head in a shape that has as few retention areas as possible for the mixture. After foreign matter is removed by a filter medium such as a wire mesh or glass beads in a filter layer provided in the spinning head if necessary, the mixture is discharged from a spinneret, air-cooled, and an oil agent is applied, followed by detection. Winding speed is usually 400 to 1500 m/
min is used.

The strength of the urethane thread wound onto the spinning bobbin may be poor immediately after spinning, but it may become weaker while it is left at room temperature (for example, 2
(time to 6 days), the strength is improved, and the recovery properties from elongation at high temperatures are also improved. The reason why the yarn quality and thermal performance of the polyurethane elastic yarn spun as described above change over time is that the reaction of the prepolymer compound mixed with the thermoplastic polyurethane elastomer used as the spinning raw material is completed during spinning. It is presumed that this is because the process proceeds even after spinning without any separation.

This reaction is believed to be the formation of a branched or crosslinked polymer due to allofunate bonds between the polyurethane and the prepolymer compound.

Hereinafter, preferred embodiments of the present invention will be summarized and described. The difunctional polyol component is selected from the group consisting of polytetramethylene glycol, polypropylene glycol, polybutylene adipate diol, polycabralactone diol, and polycarbonate diol. The method according to claim 1, wherein the diol contains at least one selected diol.

(I+) Diisocyanate component is p, p+
-diphenylmethane diisocyanate.

(c) Polytetramethylene glycol or polycaprolactone diol, polybutylene adipate diol, polyhexamethylene adipate diol, polycarbonate diol, polyneopentylene, in which the polyol used in the thermoplastic polyurethane elastomer has a number average molecular weight of 500 to 6,000. at least one selected from the group consisting of polyhexamide, polyhexamethylene/vetylene adipate copolymer diol, polycarbonate/hexamethylene adipate copolymer diol, and polyneobencin/hexamethylene adipate copolymer diol. 2. The method of claim 1, wherein the polyol comprises:

(d) The method according to claim 1, wherein the chain extender used in the thermoplastic polyurethane elastomer is a glycol or triol having a molecular weight of 500 or more.

(f) The method according to claim 1, wherein the organic diisocyanate used in the thermoplastic polyurethane elastomer is p,p'-diphenylmethane diisocyanate I.

(f) The amount of the prepolymer compound added is 3 to 3 with respect to the total weight of the thermoplastic polyurethane elastomer and the prepolymer.
The method according to claim 1, wherein the amount is 0% by weight.

()) The method according to claim 1, wherein the mixing is carried out in an apparatus equipped with a static kneading element.

〔Effect of the invention〕

Since the yarn obtained by the present invention has excellent heat resistance,
It can be applied to various uses, such as socks, swimwear, foundations, etc., especially in fields where heat resistance is required.

〔Example〕

The present invention will be explained below with reference to Examples.

Example 1 65.6 parts of dehydrated polyhexamethylene adipate diol with a hydroxyl value of 54.8 and 6 parts of 1,4-butanediol
．． Put 6 parts of P and
27.7 parts of P'-diphenylmethane diisocyanate was added and reacted.

The obtained reaction product was taken out from the kneader and molded into a pellet shape using an extruder. The molded product had a relative viscosity of 2.22 in dimethylformamide at 25°C.

On the other hand, 56.8 parts of dehydrated polycaprolamide diol having a hydroxyl group value of 132 was dissolved at a temperature of 80°C in a polymerization pot with a stirrer set so that R of the prepolymer compound was 2.59. was added to 43.2 parts of P'-diphenylmethane diisocyanate and reacted for about 30 minutes to obtain a viscous prepolymer compound. Furthermore, this compound was subjected to a defoaming operation by applying a vacuum.

Using the thermoplastic polyurethane elastomer pellets and prepolymer compound thus obtained as spinning raw materials, spinning was performed using a spinning machine equipped with a polyisocyanate compound supply device and a kneading device having a stationary kneading element. A nozzle with a diameter of 0.5φ was used as a spinneret, and a filament of 40 denier was spun at a winding speed of 500 mm/min. Table 1 shows the results of spinning with varying amounts of the prepolymer compound added to the urethane yarn.

The yarn quality and heat set recovery rate in Table 1 are values measured after the spun urethane yarn bobbin was left at room temperature for 5 days. The heat set recovery rate at 190°C is the recovery rate when a 30% elongated urethane thread is heat-treated with dry heat at 190'C for 1 minute.

As shown in Table 1, if a prepolymer compound is not added, it will melt during the measurement and cannot be measured, but by adding this compound and spinning, the heat set recovery rate will increase, and therefore the heat resistance will increase. It can be seen that it has been greatly improved.

Example 2 Using the same thermoplastic polyurethane elastomer as in Example 1,
The prepolymer compound had the same raw material composition as in Example 1, but the R ratio was changed as shown in Table 2, and spinning was performed using the same apparatus as in Example 1.

Note that the amount of prepolymer added was fixed at 18 wt%.

Claims (1)

[Claims] (1) When melt-spinning a thermoplastic polyurethane elastomer, a polyurethane polymer is polymerized from a bifunctional polyol component and a diisocyanate component, and the molar ratio of NCO groups in the diisocyanate component to OH groups in the polyol component is in the range of 2 to 4. A method for producing heat-resistant urethane yarn, which comprises adding and mixing a polymer compound to molten polyurethane, followed by spinning.