JPH0269511A - Production of polyurethane solution - Google Patents

Abstract

PURPOSE:To rapidly and simply obtain the title solution having a fixed viscosity of excellent reproducibility by starting reaction of urethane prepolymer, chain extender and end terminator at a specific temperature and raising reaction temperature during reaction process under a specific condition. CONSTITUTION:In reacting (A) a urethane prepolymer containing two terminal NCO groups with (B) a chain extender comprising a bifunctional active hydrogen compound and (C) an end terminator comprising a monofunctional or bifunctional active hydrogen compound, firstly reaction between the components A and B or reaction between the components A, B and C is started at 10-50 deg.C. Then the reaction is carried out while heating the reaction solution at 0.2-20 deg.C/ minute rate of heating and finally the reaction is completed at 70-130 deg.C to give the aimed solution. In adding the component C to the reaction system, when the component B is added alone at the starting of the reaction, the addition is preferably carried out at any stage in the midst of the reaction or at the end of the reaction.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for producing a polyurethane solution that can be processed into polyurethane elastic threads, films, etc. This invention relates to a method for producing a good direct spinnable polyurethane solution in a short time.

<Prior art> Conventionally, as a method for producing a stock solution for polyurethane elastic yarn, an excess molar amount of diisocyanate was added to a polyol having a hydroxyl group at the terminal and having a number average molecular weight of 600 to 3,000.
The reaction is carried out at a temperature of 0 to 130°C to synthesize a prepolymer having isocyanate groups at both ends, and then cooled to room temperature.
Then N,N-dimethylformamide (DMF),
It is uniformly dissolved in a polar solvent such as N,N-dimethylacetamide (DMAC) or dimethyl sulfoxide (DMSO), and a difunctional active hydrogen compound capable of reacting with an isocyanate group such as hydrazine, diamine, gelcol or amino alcohol is added thereto. In addition, a method has been adopted in which a chain extension reaction is performed to obtain a polyurethane polymerization solution.

However, in this method, when using a chain extender that reacts extremely quickly with isocyanate groups such as hydrazine or aliphatic diamine, the reaction must be carried out carefully by keeping the entire reaction system at a low temperature. Furthermore, it is already well known to those skilled in the art that even if the reaction is carried out carefully, the reproducibility of the viscosity of the final polymer obtained may be poor, or the viscosity may change over time, resulting in a polyurethane solution that cannot be spun. That is what we are doing.

Conventionally, in order to improve these drawbacks, a mixture of an aliphatic monoamine and a chain extender was used to end-capped some of the isocyanate groups of the prepolymer, thereby keeping the solution and viscosity constant. How to do so (Special Public Interest Publication 1977
(Japanese Patent Publication No. 11645/1983); A method of reducing the viscosity of a reaction system that is gelatinous and difficult to stir by heating it at an appropriate temperature after completion of synthesis to a viscosity that can be spun (Japanese Patent Publication No. 11645/1983); A method has been proposed (Japanese Patent Publication No. 3472/1983) in which an equivalent or slightly insufficient amount of isocyanate groups in a prepolymer is charged and reacted, and an aliphatic monoamine and an organic acid or an amine salt thereof are added thereto.

However, even with these methods, it is difficult to suppress changes in solution viscosity over time and variations between polymerization batches.

Furthermore, as another method, a small amount of hydrazine derivative is added to the chain extender that reacts with the isocyanate group of the urethane prepolymer, and after the reaction, the final polymer is heated and aged, even if the viscosity varies after synthesis. A method of keeping the viscosity constant (Japanese Patent Publication No. 10999/1983) has also been proposed.

However, even with this method, there are problems such as variations in the constant viscosity value and the fact that the treatment takes a long time. Although the cause of the viscosity variation is not clear, it is thought to be due to slight variations in the local molar balance between the isocyanate group and the active hydrogen compound within the reaction system and non-uniformity of the temperature within the system.

In view of these points, the present inventors conducted intensive research in order to obtain a polyurethane solution with a constant viscosity that is always reproducible, and as a result, the present invention was completed.

Thus, according to the present invention, (a) a urethane prepolymer having two terminal isocyanate groups, (b) a chain extender consisting of a bifunctional active hydrogen compound that reacts with the isocyanate groups, and (c) a chain extender that reacts with the isocyanate groups. When producing a polyurethane solution by reacting a terminal capping agent consisting of a l- or difunctional active compound in a solvent, the reaction between the urethane prepolymer (a) and the chain extender (b) or the reaction between the urethane prepolymer (a) and the chain extender (b) is carried out. ) with the chain extender (b) and the terminal stopper (c) at a reaction initiation temperature of lO<0>C to 50<0>C, and then a temperature increase rate of 0.2 to 2.0°C using the reaction heat and stirring heat.
The reaction was carried out at a rate of 0.6C/min, and after the reaction was completed, the temperature was decreased from 70℃ to 1
A method for producing a polyurethane solution is provided, characterized in that the temperature is 30°C.

According to the present invention, there is no need for a cooling device or the use of special additives or chain extenders as in the past. As a polymerization method, a polyurethane solution with good reproducibility can be obtained extremely quickly and easily.

The urethane prepolymer (a) used in the method of the present invention can be any urethane prepolymer commonly used in the production of polyurethane, for example, an active hydrogen-containing group capable of reacting with an isocyanate group at the end ( For example, hydroxyl group, amino group, carboxyl group, etc.)
For example, a substantially linear polymer having a number average molecular weight of generally 600 to 3,000, preferably 1.500 to 3,000.
By reacting polymers such as polyethers, polyesters, polyamides, polyether esters, etc. with an excess of equivalents of an organic diisocyanate in a solvent or without a solvent at a temperature typically from 60°C to about 130°C. It can be prepared.

The organic diisocyanate used here may be any type of diisocyanate, such as aliphatic, alicyclic, or aromatic, but aromatic diisocyanates are generally preferred; for example, 1,3-phenylene diisocyanate. ,1
．． 4-phenylene diisocyanate, 2.4-)lylene diisocyanate, 2.6-lylene diisocyanate, 1,5-naphthalene diisocyanate, 4.4-biphenyl diisocyanate, 3,3'-dimethyl-4,4
'Bisphenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,27-cymethyl-44
'-diphenylmethane diisocyanate and the like.

The urethane prepolymer thus prepared is then dissolved in a polar organic solvent such as dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), etc. to a suitable concentration, e.g. It can be a dope of about 30 to 40% by weight, preferably about 30 to 40% by weight.

To this dope, chain extender (b) or chain extender (b)
) and a terminal capping agent (c) are added and allowed to react. When only the chain extender (b) is added at the beginning of the reaction, the terminal capper (c) can be added at any stage during the reaction or at the end of the reaction. Chain extender (b) and/or terminal stopper (
c) or a mixture thereof may be added to the dope as is, or may be added after being diluted with a polar organic solvent as described above. When added diluted, the concentration of the chain extender (b) is generally in the range of 0.75 to IO% by weight, and the concentration of the terminal stopper (c) is generally in the range of 0.25 to 0.35% by weight. It is convenient to do so.

As the chain extender, those generally used as chain extenders for polyurethane can be similarly used, such as elendiamine, propylene diamine, butylene diamine, hexenediamine, hexamethylene diamine, l
-isopropylethylenediamine, -methyl-trimethylenediamine, l-methyl-tetramethylenediamine, l.

Aliphatic diamines such as 3-dimethyltetramethylene diamine; aromatic diamines such as xylylene diamine; glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, and 1,6-hexanediol; hydrazine, β-amino Examples include propionic acid hydrazide.

In addition, as a terminal capping agent, monoethylamine, monoethylamine, monobutylamine, diethylamine, dipropylamine, dibutylamine, allylethylamine,
Examples include primary or secondary monoamines such as benzylamine.

The amounts of these chain extenders and terminal terminators used are not strictly limited and can be changed as appropriate depending on their types and the type of urethane prepolymer, but in general, urethane prepolymers (a ) The chain extender can be used in an amount of 0.72 to 0.98 equivalents, and the end capping agent can be used in an amount of 0.08 to 0.28 equivalents.

When adding a chain extender, it is possible to add only the chain extender first, and then add the end capping agent at an appropriate step. A termination agent may be added at the same time. Furthermore, only a portion of the chain extender may be added at the beginning, and the remainder of the chain extender and the terminal capping agent may be added midway through. In any addition mode, in the present invention, the reaction initiation temperature is maintained at 10°C to 50°C while uniformly mixing.
℃, and then the temperature increase rate was 0゜2 due to reaction heat and stirring heat.
Raise the temperature at ~2.0°C/min until the final reaction temperature is 70°
It is important to keep the c-t temperature at 30°C.

Therefore, in the method of the present invention, for example, the temperature of the urethane prepolymer dope is adjusted from 10°C to 50°C at the start of the reaction.
℃, preferably within the range of 15°C to 40°C, and add a chain extender alone or in combination with a chain extender and a terminal capper. By this addition, the reaction starts and generates reaction heat, so this reaction heat and stirring heat are used to increase the temperature of the reaction mixture, and the final reaction temperature is 70° to 130°C.
1, preferably within the range of 90°O to 130°C. At that time, the temperature increase rate can be adjusted to 0.001 by controlling the amount of chain extender and/or terminal stopper added.
It is important to control the reaction temperature within the range of 2 to 2.0°C/min, preferably 0.5 to 1.5°C/min.

It is preferable to carry out the reaction with vigorous stirring to avoid heterogeneous reactions, and it is also preferable to add the chain extender and terminal stopper gradually so that they are dispersed as quickly as possible, and the addition time depends on the amount added. It depends, but usually 1-5
It can be about an hour.

In addition, in this specification, "temperature increase rate" is expressed by the following formula % formula % (
) is calculated by

After the reaction is completed, the reaction mixture can be used as it is as a stock solution that can be used for spinning. Further, a solvent may be added as necessary to form a stock solution for spinning.

In the above reaction, the viscosity of the reaction mixture may temporarily increase suddenly during the reaction, but this increase in viscosity decreases again as the temperature in the system increases, so it is possible to constantly stir the reaction mixture during the reaction process, and the viscosity is uniform. Polymerization reactions can be carried out.

Thus, according to the method of the present invention, there is no need for a conventional cooling device for lowering the reaction temperature during the reaction, and the time required for cooling the reaction solution is also unnecessary, so that the time can be shortened; Compared to conventional methods of cooling, there is less temperature difference between the inside and outside of the reaction system, so polymerization can be carried out in a uniform state; because the temperature of the polyurethane solution is high at the end of the reaction, the viscosity of the reaction mixture is low, and the stirring device It can be discharged without leaving any residue; a number of advantages are obtained.

Furthermore, the polyurethane solution obtained by the method of the present invention is stable with little change in viscosity over time and has good reproducibility, and the polyurethane elastic thread obtained from this solution has good physical properties.

Next, the present invention will be explained in more detail with reference to Examples.

Example l Polytetramethylene glycol 2 with an average molecular weight of 1950
374g and diphenylmethane diisocyanate) 552
g with stirring in a nitrogen stream at 90°C,
Stir for an hour. After cooling the obtained prepolymer having terminal isocyanate groups to 50° C., 6820 g of purified dimethylacetamide at 20° C. is added and stirred for 20 minutes to completely dissolve.

The temperature of this urethane prepolymer dope was set at 30°C, and a chain extender was added to start the reaction. The chain extender was 27g of ethylenediamine and 65g of dimethylacetamide IO.
A chain extender-containing solution at 20° C. is gradually added dropwise over 60 minutes under a nitrogen stream with vigorous stirring to cause a reaction. The temperature at this time was 48°C.

Further, a solution containing a chain extender and a terminal capper at 20° C., prepared by dissolving 26 g of ethylenediamine as a chain extender and 5 g of di-butylamine as a terminal capper in 1050 g of dimethylacetamide, is gradually added and reacted for 60 minutes. As the solution containing the chain extender and terminal capper is added dropwise, the polymer solution becomes thicker and the temperature of the contents rises. Immediately after the completion of dropping, the viscosity becomes quite high and it becomes difficult to maintain fluidity, but when the solution temperature reaches 120° C., the fluidity gradually increases and the viscosity decreases. The time when the dropwise addition was completed was defined as the time when the reaction was completed.

The temperature at this time was 125°C. Immediately after completion, the solution was taken out and allowed to cool to room temperature until the viscosity was 330 boids (30°C).
) was obtained.

This solution was left at room temperature for one month, but almost no change in viscosity was observed.

The polyurethane solution thus obtained was heated to 0.
．． The material was extruded from a 2 mΦ nozzle into an air stream heated to 200°C in a 4 m spinning cylinder, and wound up at a spinning speed of 200 m/win. The physical properties of the elastic yarn thus obtained were 42 denier, strength 1°21 g/d, and elongation 500%.

Example 2 Polytetramethylene glycol 3 with average molecular weight 1750
180g and 770g of diphenylmethane diisocyanate
A urethane prepolymer solution was obtained in the same manner as in Example 1 by reacting them in a nitrogen stream. The prepolymer concentration at this time was 40% by weight.

In contrast, 35 g of ethylenediamine as a chain extender
A chain extender solution was obtained by mixing 750 g of dimethylacetamide with 34 g of ethylenediamine as a chain extender and 5.5 g of di-n-butylamine as a terminal stopper with 800 g of dimethylacetamide. A polyurethane solution was prepared in the same manner as in Example 1 using a solution containing a terminal capping agent and a terminal capping agent.

The reaction of the polyurethane solution was completed at 125°C. Thereafter, after cooling to 30° C., 1920 g of dimethylacetamide was added and stirred to make a uniform solution with a concentration of 30% by weight, and then taken out.

The viscosity of this solution was 740 voids (30° C.), the viscosity showed little change over time, and the solution had good spinnability.

The physical property value of the 40 denyl elastic yarn obtained from this polyurethane solution was a strength of 1.6 g/d.

Example 3 Polyurethane glycol 2440 with average molecular weight 1950
g and 560 g of diphenylmethane diisocyanate were reacted in a nitrogen stream to obtain a urethane prepolymer solution in the same manner as in Example 1. The urethane prepolymer concentration at this time was 35% by weight.

On the other hand, 47g of ethylenediamine was dissolved in 1820g of dimethylacetamide, and the mixture was heated to 90% while stirring.
It was added dropwise over a period of minutes. Then, di-n-butylamine 2
2.2 g was dissolved in 392 g of dimethylacetamide, added in one shot, and the reaction continued for 5 minutes, then the contents were taken out and allowed to cool to room temperature. The viscosity of this solution was 160 poise (300C). This solution showed little change in viscosity over time and had good spinnability.

Example 4 Polytetramethylene glycol 2 with an average molecular weight of 1900
430g and 550g of diphenylmethane diisocyanate
were reacted in a nitrogen stream to obtain a urethane prepolymer solution in the same manner as in Example 1. The urethane prepolymer concentration at this time was 30% by weight.

On the other hand, 44.8 g of ethylenediamine and di-n-
Butylamine IO, 1 g and dimethylacetamide 21
A mixed chain lengthening agent solution was prepared by dissolving 66g of the chain lengthening agent, and the mixture was added dropwise over 210 minutes.

The solution temperature at the end of the dropwise addition was 73° C. After stirring for 5 minutes after the end of the dropwise addition, the contents were taken out and allowed to cool to room temperature.

The viscosity at this time was 480 poise (30°C). This solution showed little change in viscosity over time and had good spinnability.

Claims (1)

[Claims] (a) a urethane prepolymer having two isocyanates at the ends; (b) a chain extender consisting of a bifunctional active hydrogen compound that reacts with isocyanate groups; and (c) a mono- or difunctional active hydrogen compound that reacts with isocyanate groups. When producing a polyurethane solution by reacting a terminal capping agent consisting of a compound in a solvent, the reaction between the urethane prepolymer (a) and the chain extender (b) or the reaction between the urethane prepolymer (a) and the chain extender (b) ) and terminal stopper (c) at a reaction initiation temperature of 10°C to 50°C, and then reacted at a temperature increase rate of 0.2 to 2.0°C/min using the reaction heat and stirring heat to complete the reaction. A method for producing a polyurethane solution, characterized in that the temperature is 70°C to 130°C.