JP3289823B2 - Method for producing polyurethane elastic body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyurethane elastic material which has small process fluctuations in a polymerization reaction and small variations in properties.

[0002]

2. Description of the Related Art An excess molar amount of a diisocyanate compound is reacted with a polyol such as a polyester polyol or a polyether polyol having a hydroxyl group at a terminal to synthesize an intermediate polymer having an isocyanate group at both terminals. Polyurethane elastomers obtained by reacting a chain extender such as a low molecular weight diol or a diamine compound having an active hydrogen that can easily react with a group have chemical resistance, strength and abrasion resistance in addition to high elastic properties. Because of its excellent physical properties and light resistance, it is molded into fibers and films, and is widely used for various purposes.

In the production of such a polyurethane elastomer, a chain extension reaction for reacting an intermediate polymer with a low molecular weight diol, a diamino compound or the like is performed by detecting the viscosity, line pressure, etc. of the completed polyurethane elastomer or polyurethane elastomer solution. It is common to control the polymerization by adjusting the amount of a chain extender to be added based on the determination of the isocyanate group equivalent by titration of an intermediate polymer partially withdrawn from the line or the like.

However, in such a method, in the former case, the detection value is insufficient in terms of precision to perform stable polymerization control, and in the latter case, the detection value cannot be obtained in real time and continuously. As a result, strict polymerization control cannot be performed, and as a result, process fluctuations cannot be sufficiently absorbed, so that the characteristics of the produced polyurethane elastic body vary. In particular, the production of a polyurethane elastic body having an amino group and a urea group derived from a secondary monoamine compound as a terminal group and having a high molecular weight by molding with heating or heat treatment after molding, that is, a so-called post-polymerizable polyurethane elastic body. In the case of, the process variation causes a change in the abundance ratio of both terminal groups and, consequently, a change in the post-polymerization performance.

As a method for real-time and continuous determination of the isocyanate group equivalent without extracting the intermediate polymer from the line, there is a method using a process near-infrared spectrophotometer. The quantitative determination of the isocyanate group equivalent based on the above was insufficient in terms of precision to perform stable polymerization control.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, that is, in the production of a polyurethane elastomer, the isocyanate group equivalents are removed in real time without removing an intermediate polymer from a line. It is an object of the present invention to provide a method for producing a polyurethane elastic material having a small variation in properties by controlling the polymerization amount by adjusting the amount of a chain extender added based on the detected value and controlling the polymerization to absorb the process variation.

[0007]

Means for Solving the Problems The present inventors have intensively studied, studied, and studied to solve the above-mentioned problems, and as a result, have finally completed the present invention. That is, the present invention is a method for producing a polyurethane elastomer by reacting a polyol with an excess molar amount of a diisocyanate compound to synthesize an intermediate polymer having a terminal isocyanate group, and then subjecting this to a chain extension reaction to produce a polyurethane elastomer. Polyurethane elasticity characterized by quantifying the terminal isocyanate group equivalent of an intermediate polymer with a process infrared spectrophotometer that can be measured in a quantitative manner, and controlling the polymerization by adjusting the amount of a chain extender added based on the detected value. It is a method of manufacturing the body.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention are as follows. When determining the terminal isocyanate group equivalent of the intermediate polymer,
The method for producing a polyurethane elastic body according to the above, wherein the intermediate polymer is in a solution state. When the polyurethane elastomer has an amino group (A)
And the method for producing a polyurethane elastic body according to the above, which has a urea group (B) derived from a secondary monoamine compound which is a terminal stopper. When the polyurethane elastomer has an amino group (A)
And a urea group (B) derived from a secondary monoamine compound which is a terminal terminator, and the quantitative ratio (B / A) of both terminal groups is 0.5 to 2.0. Production method.

Hereinafter, the present invention will be described in more detail. The polyurethane elastic body in the present invention is obtained by reacting a polyol such as a polyester polyol or a polyether polyol having a terminal hydroxyl group with an excess molar amount of a diisocyanate compound to synthesize an intermediate polymer having a terminal isocyanate group. When conducting a chain extension reaction with a diamino compound or the like, the terminal isocyanate group equivalent of the intermediate polymer is quantified by a process infrared spectrophotometer that can be continuously measured, and the amount of the chain extender added is adjusted based on the detected value. By performing polymerization control in this way, the production is stabilized.

In the present invention, the infrared spectrophotometer used for determining the terminal isocyanate group equivalent of the intermediate polymer comprises:
Even without extracting some of the intermediate polymer out of the polymerization system,
There is no particular limitation on the process infrared spectrophotometer that can be continuously measured online. For example, a process infrared spectrophotometer manufactured by Applied Systems, a process infrared spectrophotometer manufactured by Shimadzu Corporation, and the like are exemplified.

The detection of the terminal isocyanate group equivalent of the intermediate polymer is carried out from the completion of the synthesis of the intermediate polymer to before the chain extension reaction, and it is preferable that the reaction is as close as possible to the chain extension reaction in terms of time. If it is necessary to detect the terminal isocyanate group equivalent of the intermediate polymer during the period from the completion of the synthesis of the intermediate polymer to the time before the chain extension reaction, a plurality of positions between the synthesis process of the intermediate polymer and the time before the chain extension reaction are performed. Alternatively, a plurality of detections may be performed. However, the detection value used for controlling the polymerization by adjusting the amount of the chain extender to be added is desirably a detection value as close to the chain extension reaction as possible over time. . The intermediate polymer can detect the terminal isocyanate group equivalent in either a molten state or a solution state, but is preferably in a solution state from the viewpoints of fluidity, detection accuracy, and the like of the intermediate polymer.

The structure of the terminal isocyanate group equivalent detecting portion of the intermediate polymer is not particularly limited as long as the intermediate polymer is not partially extracted from the polymerization system to the outside of the system. For example, a structure in which the probe end of the process infrared spectrophotometer is directly inserted into the polymerization system, an intermediate polymer circulation line for extracting the intermediate polymer by a gear pump and returning it to the polymerization system, and providing a line for process infrared spectroscopy A structure in which a detection end probe part of a photometer is inserted is exemplified.

[0013] The polymerization control performed based on the detected value of the terminal isocyanate group equivalent of the intermediate polymer, provided that a feedforward circuit for adjusting the addition amount of the chain extender based on the detected value of the terminal isocyanate group equivalent is included. There is no particular limitation. For example, first, the molecular weight of the intermediate polymer is calculated from the molecular weight of the polyol and diisocyanate compound and the charged amount and the detected value of the terminal isocyanate group equivalent, and then the molecular weight of the target polyurethane elastomer, the molecular weight of the intermediate polymer, and the terminal isocyanate group are calculated. From the base equivalent,
By a method such as determining the amount of the chain extender to be added, stable polymerization with small process variations can be achieved.

In particular, a polyurethane elastic material having an amino group (A) and a urea group (B) derived from a secondary monoamine compound as a terminal group of the polyurethane elastic material, and having a high molecular weight by molding with heating or heat treatment after molding. The effect of the present invention is remarkable in the production of a polyurethane elastic body having a so-called post-polymerization property. In this case, the terminal isocyanate group equivalent of the intermediate polymer and the terminal isocyanate are adjusted so that the ratio B / A of the polymer terminal groups is in the range of 0.5 to 2.0, preferably 0.7 to 1.5. It is preferable to carry out the reaction by adjusting the addition amounts of the diamine compound as the chain extender and the secondary monoamine compound based on the molecular weight of the intermediate polymer calculated from the group equivalent. If the ratio B / A of the polymer end groups is less than 0.5 or more than 2.0, sufficient physical properties cannot be exhibited by molding with heating or heat treatment after molding.

[0015] The polyol used in the present invention is not particularly limited. For example, polymer diol and the like can be mentioned. Specifically, polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, polyoxypentamethylene glycol,
A polyether diol such as polyoxypropylene tetramethylene glycol; one or more dibasic acids such as adipic acid, sebacic acid, maleic acid, itaconic acid, azelaic acid, and malonic acid; and ethylene glycol;
-Propylene glycol, 1,3-propylene glycol, 2,2-dimethyl-1,3-propanediol,
Polylactone diols such as polyester diols, poly-ε-caprolactone and polyvalerolactone obtained from one or more glycols such as 1,4-butanediol, 2,3-butanediol, hexamethylene glycol, diethylene glycol, etc. And polyester amide diol, polyether ester diol, polycarbonate diol and the like. The number average molecular weight of the polyol is usually about 500 to 6000, preferably 1,000 to 5,000, more preferably 1,000 to 5,000.
3000. If the number average molecular weight is less than 500, the elasticity of the resulting elastic yarn tends to be insufficient,
Conversely, if it exceeds 6000, mechanical properties such as strength and elastic recovery tend to be insufficient.

The diisocyanate compound is not particularly limited, as long as it is soluble or liquid under the reaction conditions among aliphatic, alicyclic and aromatic diisocyanates. For example, methylene-bis (4-phenylisocyanate), methylene-bis (3-methyl-4-phenylisocyanate), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m- and p-
Phenylene diisocyanate, m- and p-xylylene diisocyanate, methylene-bis (4-cyclohexyl isocyanate), 1,3- and 1,4-cyclohexylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, etc. Can be mentioned. Among them, methylene-bis (4
-Phenylisocyanate) is preferred.

The above-mentioned reaction between the polyol and the diisocyanate compound is carried out in such a manner that the diisocyanate compound is mixed in an excess molar amount, and preferably the equivalent ratio of the isocyanate group to the hydroxyl group is in the range of 1.3 to 3.0, more preferably. The mixing is performed in the range of 1.5 to 2.0, and the reaction is carried out at a temperature of 60 to 120 ° C., whereby an intermediate polymer having isocyanate groups at both terminals is obtained. At this time, as the polyol and the diisocyanate compound, two or more kinds can be used as long as the physical properties of the obtained polyurethane elastic body are not impaired. In addition, a small amount of a low molecular weight diol such as ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol and the like and water can also be used.

The low molecular weight diol or diamine compound used as a chain extender is not particularly limited. For example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-bis (β-hydroxyethoxy) benzene, xylylene glycol, hydrazine, ethylenediamine, One or more of propylenediamine, trimethylenediamine, hexamethylenediamine, 1,4-cyclohexanediamine, xylylenediamine, isophoronediamine, piperazine, phenylenediamine and the like can be used.

A monoalcohol compound during the chain extension reaction,
The secondary monoamine compound may be mixed with a chain extender, or a monoalcohol compound or a secondary monoamine compound may be added after the completion of the chain extension reaction. As the monoalcohol compound used, for example, methanol, ethanol, 1-
Propanol, 2-propanol, 1-butanol, 2
-Butanol, 1-pentanol, 2-pentanol,
3-pentanol, cyclopentanol, cyclohexanol, cycloheptanol and the like, and as the secondary monoamine compound, for example, dimethylamine, diethylamine, diethanolamine, diisopropylamine, di-n-butylamine, methylethylamine, methyl- Isopropylamine, dicyclohexylamine and the like can be mentioned, and the monoalcohol and the secondary monoamine can be used alone or in combination of two or more.

The chain extension reaction may be performed in the presence of an inert organic solvent. The inert organic solvent to be used is not particularly limited as long as it can dissolve the above-mentioned raw materials and the intermediate polymer and can dissolve or disperse the produced polyurethane elastic material. For example, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide and the like can be mentioned. Preferably, it is N, N-dimethylacetamide.

To the obtained polyurethane, a known organic or inorganic compounding agent having a specific chemical structure is added and supplied to a melt or dry or wet spinning machine or molding machine to obtain fibers or films. Can be. Examples of the organic or inorganic compounding agent include light-fastening agents such as benzophenone-based compounds, benzotriazole-based compounds, and hindered amine-based compounds, yellowing inhibitors such as tertiary amine-containing compounds, semicarbazide-based compounds, and hindered phenol-based compounds. Antioxidants, inorganic fine particles such as barium sulfate, magnesium silicate, calcium silicate, zinc oxide, magnesium oxide, anti-adhesives such as magnesium stearate, polytetrafluoroethylene, organopolysiloxane,
Fungicides and the like.

[0022]

EXAMPLES The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples. In the following examples, logarithmic viscosity, strong elongation,
Heat resistance was measured by the following method.

Preparation of a sample for logarithmic viscosity measurement: About 1 g of the sample was treated with boiling water for 1 hour and air-dried. This is used as a sample after the boiling water treatment. On the other hand, a sample that has not been subjected to heat treatment is an untreated sample.

Measurement of logarithmic viscosity: 0.075 g of each of the untreated sample and the sample after the boiling water treatment were treated with 25 ml of N, N-dimethylacetamide (provided that only 0.05 N dibutylamine / N, N -Dimethylacetamide solution 25 ml), and 10 ml of each of these solutions was taken on an Ostwald viscometer,
And the logarithmic viscosity (η _inh ) was calculated from the following equation. In the equation, t is the number of seconds the sample solution falls (seconds), t ₀ is the number of seconds the solvent falls (seconds) and C
Represents the concentration (g / dl) of the sample solution, respectively.

[0025]

(Equation 1)

Measurement of strength and elongation: Toyo BOL
The film was stretched by Tensilon manufactured by DWIN, and the strength and elongation at break were measured.

Measurement of heat resistance: A sample having an initial length of 9.5 cm was dried at 190 ° C. with a thermosetter under 100% elongation.
And then heat-treated for 1 minute with a dyeing machine.
After heating for 60 minutes from 130 ° C to 130 ° C, the sample was continuously treated at 130 ° C for 60 minutes, and then a 5 cm sample was stretched with Tensilon manufactured by Toyo BOLDWIN, and the strength at break was measured. Sex was calculated. Heat resistance (%) = {Strength after heat treatment / Strength before heat treatment} x
100

Example 1 Immediately before the chain extension reaction, a polyoxytetramethylene glycol having a molecular weight of 1800 and methylene-bis (4-phenyl) were introduced into a continuous polymerization apparatus equipped with a detection end probe of a process infrared spectrophotometer manufactured by Applied Systems. Isocyanate)
Was mixed and supplied continuously at a molar ratio of 1: 2 in excess of isocyanate, and reacted at 80 ° C. for 2 hours to obtain an intermediate polymer having isocyanate groups at both terminals. Continuously, the terminal isocyanate group equivalent of the intermediate polymer was continuously measured by an installed process infrared spectrophotometer, and based on the detected value, 1,4-
Butanediol is continuously supplied to the twin-screw extruder while being automatically adjusted by a feedforward circuit, and the
Perform continuous melt polymerization at ℃, continuously supply and mix UV absorber, anti-yellowing agent, antioxidant, anti-adhesive, etc.
The resulting polyurethane elastic body was extruded into water in the form of a strand and cut into pellets. 8 pellets
It was dried at 0 ° C. for 24 hours under a nitrogen stream. The pellets were spun at a spinning temperature of 207 ° C. and a spinning speed of 500 using a spinning machine of a single screw extruder.
Under the conditions of m / min, a monofilament, 40 denier polyurethane elastic yarn was obtained. With the above method and conditions,
Polymerization and spinning were performed continuously for two weeks. The logarithmic viscosity of the yarn for the representative 7 cheeses with different sampling times each day,
The elongation and heat resistance were measured. Table 1 shows the two-week average value and the variation between cheeses (n = 98 in each case) for each measured value. All of the properties were stable with good values, and a polyurethane elastic yarn with small variation was obtained.

Example 2 Immediately before the chain extension reaction, a polyoxytetramethylene glycol having a molecular weight of 1800 and methylene-bis (4-phenyl) were introduced into a continuous polymerization apparatus equipped with a detection end probe of a process infrared spectrophotometer manufactured by Applied Systems. Isocyanate)
Is mixed and supplied at a molar ratio of 1: 1.62 of an excess of isocyanate, and reacted at 80 ° C. for 3 hours to obtain an intermediate polymer having both terminal isocyanate groups.
After cooling to 0 ° C, N, N-dimethylacetamide was supplied so that the intermediate polymer concentration became 40% to dissolve the intermediate polymer, and then cooled to 10 ° C. Continuously, with a process infrared spectrophotometer installed immediately before performing the chain extension reaction, continuously measure the terminal isocyanate group equivalent of the intermediate polymer,
Based on the detected value, the viscosity of the polyurethane elastic solution 2
The amount ratio (B / A) of 500 poise (30 ° C.) and the urea group (B) derived from an amino group (A) and a secondary monoamine compound which is a terminal terminator has an end group of 0.9 and 0.9. A solution prepared by dissolving ethylenediamine and diethylamine in N, N-dimethylacetamide, respectively, was supplied and mixed while automatically adjusting the feedforward circuit so that the polyurethane elastic material concentration was 32.3%.
Was obtained. Continuously, an ultraviolet absorbent, an anti-yellowing agent, an antioxidant, an anti-adhesive agent, and the like were supplied to the polyurethane elastic solution and mixed to obtain a spinning dope having a viscosity of 2000 poise (30 ° C.). The undiluted spinning solution is extruded from a spinneret into a spinning tube in which heated air at 230 ° C. is flown, wound up on a bobbin under a spinning speed of 500 m / min, and then heated at 40 ° C. for 72 hours while being wound on the bobbin. A polyurethane elastic yarn of 4 filaments and 40 denier was obtained.
Under the above method and conditions, polymerization and spinning were continuously performed for two weeks. The logarithmic viscosity, strength and elongation, and heat resistance of the yarn were measured for seven representative cheeses having different collection times each day. Table 1 shows the two-week average value and the variation between cheeses (n = 98 in each case) for each measured value. All of the properties were stable with good values, and a polyurethane elastic yarn with small variation was obtained.

Comparative Example 1 In Example 1, the polymerization was controlled by feeding back the amount of the chain extender supplied based on the detected value of the melt viscosity at the outlet of the extruder without installing a process infrared spectrophotometer in the polymerization apparatus. Except for the above, polymerization and spinning were carried out continuously for 2 weeks under the same method and under the same conditions as in Example 1. In the same manner as in Example 1, the logarithmic viscosity, strength and elongation, and heat resistance of the yarn were measured for seven representative cheeses having different collection times each day. Table 1 shows the two-week average value and the variation between cheeses (n = 98 in each case) for each measured value. All of the characteristics exhibited good values in average, but the dispersion was large.

Comparative Example 2 In Example 2, polymerization control was performed by not feeding a process infrared spectrophotometer to the polymerization apparatus, but feeding back to the supply amount of the chain extender based on the detected value of the solution viscosity after the completion of the chain extension. Polymerization and spinning were performed continuously for two weeks under the same method and under the same conditions as in Example 2 except for the above. As in Example 2, the logarithmic viscosity, strength and elongation, and heat resistance of the yarn were measured for 7 representative cheeses having different collection times each day. Table 1 shows the two-week average value and the variation between cheeses (n = 98 in each case) for each measured value. All of the properties varied greatly, and particularly, the post-polymerization property and the heat resistance were affected on average.

[0032]

[Table 1]

[0033]

According to the conventional method for producing a polyurethane elastic body, since the process fluctuation in the polymerization reaction cannot be sufficiently absorbed, the characteristics of the obtained polyurethane elastic body vary widely. Particularly, molding involving heating and heat treatment after molding are performed. In the production of a polyurethane elastic body having a high molecular weight by so-called, a polyurethane elastic body having a so-called post-polymerization property, a process variation that cannot be absorbed sufficiently causes a variation in post-polymerization performance.
Significant variations occur in the properties of the polyurethane elastomer.
On the other hand, the method for producing a polyurethane elastic body of the present invention comprises:
Since the process variation in the polymerization reaction can be absorbed, even a polyurethane elastic body having post-polymerization properties can be obtained with a small variation in its characteristics.

Claims (4)

(57) [Claims] 1. A method for producing a polyurethane elastomer by reacting a polyol with an excess molar amount of a diisocyanate compound to synthesize an intermediate polymer having a terminal isocyanate group, and then subjecting the intermediate polymer to a chain extension reaction. Polyurethane elasticity characterized by quantifying the terminal isocyanate group equivalent of an intermediate polymer with a process infrared spectrophotometer that can be measured in a quantitative manner, and controlling the polymerization by adjusting the amount of a chain extender added based on the detected value. How to make the body. 2. The method according to claim 1, wherein the intermediate polymer is in a solution state when the terminal isocyanate group equivalent of the intermediate polymer is determined. 3. The polyurethane elastomer according to claim 1, wherein the polyurethane elastomer has an amino group (A) as a terminal group and a urea group (B) derived from a secondary monoamine compound as a terminal terminator. Method. 4. The polyurethane elastomer has an amino group (A) as a terminal group and a urea group (B) derived from a secondary monoamine compound which is a terminal terminator, and has a quantitative ratio (B) of both terminal groups.
The method for producing a polyurethane elastic body according to any one of claims 1 to 3, wherein / A) is from 0.5 to 2.0.