KR100273189B1 - The process for preparing polyurethane elastomer having excellent physical properties and heat resistance - Google Patents

Abstract

The present invention relates to a method for producing an elastic fiber composed of polyurethane, which is condensation-polymerized to a weight average molecular weight of 1,800 g / mol using a 4-4 'diphenylmethane diisocyanate compound, adipic acid and 3-methylpentane diol Polyurethane polymerization with polyester polyol and bishydroxy ethylbenzene and condensation polymerization of 4,4'-diphenylmethane diisocyanate compound, adipic acid and 3-methylpentane diol with weight average molecular weight of 1,800 g / mol After preparing a crosslinking agent using a polyester polyol, the crosslinking agent of 10 to 20wt% is added and spun on the molten polyurethane, and the elastic yarn prepared by the method of the present invention is characterized by tensile strength, elongation and elasticity. Physical properties such as recovery rate and heat resistance, and radioactivity and maritime resistance were significantly improved.

Description

Manufacturing method of polyurethane elastic fiber with excellent heat resistance and physical properties

The present invention relates to a method for producing an elastic fiber composed of polyurethane, and more particularly, to a polyurethane elastic fiber that exhibits excellent mechanical properties, elastic recovery power and high heat resistance by a melt spinning method.

Polyurethane-based elastic fibers are excellent in elasticity and elastic recovery power, and are widely used in stockings, women's underwear, and stretch fabrics, and their use continues to expand.

Polyurethane elastic yarn production includes a wet method, a dry method, a melting method and a polymerization spinning method. These methods have their own characteristics, but from an economical point of view and an industrial point of view, because of the flexibility, compatibility and solvent of the device, the melt spinning method compared with other methods in the production of polyurethane fibers such as the simplicity of spinning method This has many advantages.

However, polyurethane elastic fiber is poor in heat resistance, so when mixed with other materials such as polyester fiber, when dyed at a high temperature at 130 ° C, physical properties such as elastic recovery power and strength are deteriorated, making it impossible to use. Follow.

In general, the elastic fibers produced by the dry method or the wet method and the polymerization spinning method are excellent in elastic recovery at high temperature because it contains a urethane group and a urea group at the same time. However, in the case of containing urea group, melt spinning is impossible because it is not melted by the physical secondary bonding between the urea groups. Therefore, elastic fibers are inevitably produced by the spinning method using a solvent. Since the spinning method uses a solvent, the spinning method is difficult, and a large investment in manufacturing equipment is required.

The production of elastic fibers by melt spinning is very advantageous from an industrial point of view because it does not use a solvent and the spinning method is simple. However, polyurethane elastic fibers composed solely of polyurethane groups have low thermal stability and thus cannot be used at high temperatures.

Conventional methods for improving the heat resistance of polyurethane elastic fibers include adding a polyol having three hydroxyl groups to a polyol having two hydroxyl groups, polymerizing the prepolymer, and then performing a chain extension reaction using a chain extender having two hydroxyl groups. There is a method of obtaining a partially cross-linked polyurethane by proceeding to melt spinning it (Japanese Patent No. 49-48677).

Another method is to obtain a partially cross-linked polyurethane using a polyol having three hydroxyl groups or a chain extender after the prepolymer polymerization, and melt spinning it (Japanese Patent Application No. 43-7426, Japanese Patent Laid-Open No. 7-70278). ).

The method of introducing chemical crosslinks into a polyurethane using an organic compound having three hydroxyl groups as described above has disadvantages in that the melt state is uneven during spinning and the melt viscosity becomes very high. If the molten state is uneven, the uniformity of the spun yarn is reduced and workability is reduced. In addition, when the melt viscosity is increased, the spinning temperature should be increased in order to spin, but if the spinning temperature is higher than 250 ° C., thermal decomposition of the polyurethane may occur, and thus the final physical properties may be reduced by lowering the molecular weight.

Another method of introducing a chemical crosslink into a polyurethane without using an organic compound having three hydroxyl groups is to form an intermediate polymer of terminal isocyanate, and then use terminal treatment agents such as diol or diamine to form terminal isocyanate groups. The interpolymers are treated to treat residual isocyanate groups.

Method of producing a crosslinked polyurethane elastic yarn by melt-spun spinning the treated intermediate polymer to melt filaments to form a filament, then through a cross-linking treatment bath with a swelling agent and a crosslinking agent and undergoing a crosslinking reaction by heat treatment in a stream of nitrogen. There is this (Japanese beef 42-19499).

The method presented above is troublesome to separate the precipitated interpolymer separately by treating the intermediate polymer with an end treatment agent and then precipitating in water. In addition, the method of passing the spun polyurethane filament through the crosslinking agent treatment bath is very complicated, and since the solvent is used as a swelling agent in the crosslinker treatment bath, the solvent must be removed later. In addition, since the crosslinking agent is mainly present on the surface of the filament, crosslinking reaction between the filaments proceeds by the reaction between the crosslinking agents present on the surface of the filament, so that the dissolution property of the filament after winding is poor.

The present invention is a polyurethane elasticity having excellent radioactivity and heat resistance mainly composed of allophanate groups by adding and mixing an intermediate polymer having an isocyanate group at the end to a polyurethane melt-injected as a crosslinking agent and proceeding a crosslinking reaction in a polyurethane filament. The purpose is to produce fibers.

The present invention is obtained by reacting a polyester polyol with a diisocyanate to obtain a polyurethane interpolymer, followed by a chain extension reaction using an alkane-based diol compound as a chain extender to react with a polyurethane, a polyester polyol, and a diisocyanate. By adding and mixing an intermediate polymer having an isocyanate group as a crosslinking agent to the melted polyurethane in melt spinning, a polyurethane elastic fiber excellent in spinning and heat resistance mainly composed of malofane groups can be obtained.

Specifically describing the present invention, after reacting 1 mole of a linear high molecular weight diol compound having a weight average molecular weight of 1,000 to 3,000 g / mol and 2 moles of an aliphatic or aromatic diisocyanate compound to obtain a prepolymer having an end isocyanate, Aliphatic, aromatic alicyclic diols or mixtures of these compounds having a weight average molecular weight of 500 or less are added to the intermediate polymer and reacted with an isocyanate group of the prepolymer by adding 1 mol of hydroxyl groups to the prepolymer until the viscosity of the polymerization system reaches equilibrium. To produce a polyurethane polymer. The polyurethane polymer thus obtained is made into chips of uniform size using a pelletizer.

After reacting 1 mol of a linear high molecular weight diol compound having a weight average molecular weight of 1,000 to 3000 g / mol with 2 mol of an aliphatic or aromatic diisocyanate compound to obtain a prepolymer having an isocyanate terminal, the high molecular weight polyurethane polymer obtained above is melted. In the spinning process, a predetermined amount of prepolymer having an isocyanate is added and mixed, followed by melt spinning, followed by heat treatment at 80 ° C. for 24 hours to prepare a polyurethane elastic fiber having excellent heat resistance mainly comprising an allophanate group.

In the present invention, the amount of the crosslinking agent added is preferably 10 to 20 wt% based on the polyurethane polymer. If the addition amount of the crosslinking agent is less than 10wt%, the improvement of heat resistance is insignificant, and if it exceeds 20wt%, the melt viscosity is too low to be wound and the nozzle should be replaced frequently. Diisocyanate compounds usable in the present invention include p-phenylene diisocyanate, m-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,4-tetramethylene diisocyanate, 1, 10-decamethane diisocyanate, 1,5-tetrahydroxy naphthalene diisocyanate, 1,6-hexamethylene diisocyanate, 4,4'-diphenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, etc. There are compounds, of which 4,4'-diphenylmethane diisocyanate compounds are most preferred in consideration of the reactivity with the diol compound and the physical properties of the elastomer.

There are two kinds of polyols used in the present invention, polyether polyols having a weight average molecular weight of 1,000 to 3,000 g / mol and polyester polyols. Polyether polyols include polyethylene oxide glycol, polypropylene oxide, polytetramethylene oxide glycol, polypentamethylene oxide glycol, polyhexamethylene oxide glycol, polyheptamethylene oxide glycol, polyoctamethylene oxide glycol, polynanomethylene oxide glycol and poly Decamethylene oxide glycol or glycol mixtures or copolymers thereof, and the like.

Examples of the linear polyester polyol having a hydroxyl group at the terminal include glycol components such as ethylene glycol, propylene glycol, butanediol, 3-methylenetandiol, hexanediol, and bisoxymethyl cyclohexane, and acid components such as adipic acid, terephthalic acid and isophthalic acid. Polyesters made of condensation polymerization;

In the case of producing an intermediate polymer containing a polyurethane bond, any of the above polyether type or polyester type may be used as the hydroxyl group material, or a mixed type or copolymer type thereof may be used.

Pyrolysis of polyether polyol occurs because it is required to spin at a temperature of 200 ° C. or higher during the melt spinning of a polyurethane polymerized with a polyether polyol, a diisocyanate and a diol chain extender. Therefore, since the molecular weight of the wound elastic fiber is lowered, the physical properties and heat resistance of the final elastic fiber is lowered. Therefore, in the present invention, polyester polyol is used in order to minimize molecular weight decrease due to thermal decomposition of polyether polyol.

As the polyol used in the present invention, it is preferable to use a polyester polyol in consideration of physical properties, heat resistance, and radioactivity of the final polyurethane filament, and the polyester polyol is a weight average molecular weight using adipic acid and 1,4-butanediol. It is most preferable to use the polyester polyol condensation-polymerized at this 1,000-3,000 g / mol.

Prepolymers in which a high molecular weight diol compound and a diisocyanate compound are combined can obtain a polymer having an appropriate molecular weight by using a low molecular weight diamine and a diol compound as a chain extender. When the diamine compound is used as a chain extender, the chain-extended polymer is subjected to heat. Since it is not melted by the melt spinning method, it is impossible to manufacture the elastic fiber.

Therefore, as mentioned above, the polymer using the diamine chain extender can produce an elastic fiber by dry spinning or wet spinning. However, since the melting temperature of the polymer obtained by using the diol compound as the chain extender is 200 ° C. or lower, elastic fibers can be produced by melt spinning.

Diol compounds usable as chain extenders include ethylene glycol, propylene glycol, butanediol, pentanediol, 3-methylenetandiol, hexanediol, bishydroxyethylbenzene, among these compounds, considering the physical properties and heat resistance Most preferably, bishydroxy ethylbenzene is used. Since bishydroxy ethylbenzene contains a benzene ring, the molecular chain is rigid compared to the aliphatic diol compound, which is advantageous in terms of improving physical properties and heat resistance.

The prepolymer used as the crosslinking agent in the present invention can be prepared by the reaction of a diisocyanate group with a polyol, and considering the compatibility with polyurethane, it is preferable to prepare a crosslinking agent using a polyester polyol. As the polyol, various polyols mentioned above may be used, but in the present invention, it is most preferable to use a polyester polyol condensation-polymerized with adipic acid and 3-methylpentanediol with a weight average molecular weight of 1,000 to 3,000 g / mol.

In the preparation of the prepolymer used as the crosslinking agent in the present invention, the diisocyanate is most preferably used as the 4,4'-diphenylmethane diisocyanate compound in consideration of compatibility with the polyurethane, reactivity, and physical properties.

When explaining the preferable example of this invention concretely, first, 2 mol of diisocyanate compounds and 1 mol of polyester polyols are mixed, and then the temperature of a reaction system is heated to 80 degreeC, and it reacts until the viscosity of a polymerization system reaches equilibrium. After completion of the first reaction, the temperature of the reaction system is lowered to room temperature, and a diol chain extender is gradually added.

After adding a diol chain extender, the temperature of the reaction system is raised to 200 ° C. After the secondary reaction proceeds until the viscosity of the reaction system reaches equilibrium, the polymer is brought into a chip state using a pelletizer.

The crosslinking agent is first mixed with 2 mol of the diisocyanate compound and 1 mol of the triester polyol, and then the temperature of the reaction system is raised to 80 ° C. until the viscosity of the polymerization system reaches equilibrium. After completion of the reaction, the temperature of the reaction system is reduced to room temperature and stored under the cool dark nitrogen stream.

After the polymerized polyurethane chip was dried at 100 ° C. under nitrogen stream for 12 hours, the polyurethane was melted in a melt injection machine, and then the prepolymer used as a crosslinking agent was added and mixed with the melted polyurethane, followed by spinning by melt spinning. By heat-treating at 80 ° C. for 24 hours in a nitrogen gas atmosphere, a polyurethane elastic yarn having excellent radioactivity, physical properties, and heat resistance mainly comprising allophanate groups is prepared.

Embodiments of the present invention are as follows.

Tensile strength, elongation, and elastic recovery rate shown in the Examples were evaluated according to KSK 0219, and the heat resistance was maintained at 30% elongation for 1 minute at each temperature. Degradability was evaluated by measuring the tension required to dissolve the wound polyurethane elastic fiber at a rate of 250 times per minute.

(Example 1)

To 500 g of 4,4'-diphenylmethane diisocyanate compound, 900 g of a polyester polyol condensation-polymerized using adipic acid and 3-methylpentanediol at a weight average molecular weight of 1,800 g / mol was introduced, and then the temperature was increased to 80 ° C. The mixture was heated to react until the viscosity of the reaction system reached equilibrium, thereby preparing an interpolymer having an isocyanate terminal.

After the temperature of the prepolymer was lowered to room temperature, 166 g of bishydroxy ethylbenzene was slowly added to the prepolymer at a rate of 5 g / min and mixed. After the addition of bishydroxy ethylbenzene, the temperature of the reaction system was raised to 200 ° C. and the secondary reaction was carried out until the viscosity of the reaction system reached equilibrium to polymerize a high molecular weight polyurethane, and then the size was obtained using a pelletizer. Made into a uniform chip.

The crosslinking agent was first mixed with 250 g of 4,4'-diphenylmethane diisocyanate compound, adipic acid and 3-methylpentane diol, and then 900 g of polyester polyol condensation-polymerized with a weight average molecular weight of 1,800 g / mol. The temperature was raised to 80 ° C. and reacted until the viscosity of the polymerization system reached equilibrium. After completion of the reaction, the temperature of the reaction system was lowered to room temperature and stored under a cool dark nitrogen stream.

After drying the polyurethane chip obtained by the above method at 100 ° C. under nitrogen stream for 12 hours, the polyurethane was melted in a melt injection machine, and then 15 wt% of the prepolymer used as a crosslinking agent was added to the molten polyurethane in a weight ratio. After mixing and spinning by melt spinning method to prepare a polyurethane elastic yarn of 30 men, heat treatment for 24 hours at 80 ℃ nitrogen gas atmosphere, polyurethane elastic yarn having excellent radioactivity, physical properties and heat resistance mainly composed of allophanate group Was prepared, and the physical properties and heat resistance measurement results are shown in Table 1.

(Comparative Example 1)

A polyurethane elastic yarn was prepared in the same manner as in Example 1 except for adding 8 wt% of a crosslinking agent, and the physical properties and heat resistance measurement results are shown in Table 1.

(Comparative Example 2)

A polyurethane elastic yarn was prepared in the same manner as in Example 1 except that the crosslinking agent was added 25 wt%, and the physical properties and the heat resistance measurement results are shown in Table 1.

(Comparative Example 3)

Polyurethane elastic yarns were prepared in the same manner as in Example 1 except that the crosslinking agent was prepared using polytetramethylene glycol, and physical properties and heat resistance measurement results are shown in Table 1.

(Comparative Example 4)

Except for using 1,4-butanediol without using bishydroxy ethylbenzene in the diol compound that is a chain extender during the polyurethane polymerization, and the same as in Example 1, the physical properties and heat resistance measurement results are shown in Table 1.

(Comparative Example 5)

The crosslinking agent was prepared using a 2,4-toluene diisocyanate compound instead of 4,4'-diphenylmethane diisocyanate as a diisocyanate compound, and was prepared in the same manner as in Example 1, and the physical properties and heat resistance measurement results are shown in Table 1. It was.

Tensile strength (g / d) Elongation (%) Elastic recovery rate (%) Heat resistance temperature (℃) Radioactive Maritime Example 1 1.55 610 96 190 ◎ ◎ Comparative Example 1 1.24 580 85 150 ◎ ◎ Comparative Example 2 1.68 650 96 200 × △ Comparative Example 3 1.35 580 95 170 △ × Comparative Example 4 1.43 620 94 180 ◎ ○ Comparative Example 5 1.38 560 91 160 ○ ○

◎; Very good, ○; Good, △; Usually, ×; Bad

As can be seen from the above embodiment, the elastic yarn produced by the method of the present invention has significantly improved physical properties such as tensile strength, elongation, elastic recovery rate and heat resistance temperature, and radioactivity and resolution.

Claims (4)

Polyurethane polymerization using 4-4 'diphenylmethane diisocyanate compound, adipic acid and 3-methylpentane diol with polyester polyol and bishydroxy ethylbenzene condensation-polymerized at a weight average molecular weight of 1,800 g / mol, and 4 A crosslinking agent was prepared using a polyester polyol condensation-polymerized at a weight average molecular weight of 1,800 g / mol using a, 4'-diphenylmethane diisocyanate compound, adipic acid and 3-methylpentane diol, and then melted polyurethane. 10-20 wt% of crosslinking agent is added to and mixed with the spinning to produce a polyurethane elastic yarn. The method for producing a polyurethane elastic yarn according to claim 1, wherein the polyurethane is polymerized using a polyester polyol having a weight average molecular weight of 1,000 to 3,000 g / mol for the condensation polymerization of adipic acid and 3-methylpentanediol. . The method for producing a polyurethane elastic yarn according to claim 1, wherein bishydroxy ethylbenzene is used as the chain extender. The method of claim 1, wherein the crosslinking agent prepared by using a polyester polyol having a weight average molecular weight of 1,000 to 3,000 g / mol for condensation polymerization of adipic acid and 3-methylpentanediol is added and mixed with molten polyurethane to spun. Method for producing a polyurethane elastic yarn characterized in that.