JP2001294668A - Method for producing polyketone solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of polyketone aggregates when a polyketone is dissolved in an aqueous solution containing at least one salt selected from a zinc salt, a calcium salt, a thiocyanate, and an iron salt. And a method for producing a uniform polyketone solution at high speed. SOLUTION: The salt concentration is 0.01% by weight or more and 59% by weight.
After preparing the suspension by dispersing the polyketone in the following salt aqueous solution, water is separated and removed from the suspension until the salt concentration becomes 60% by weight or more and 90% by weight or less to produce a polyketone solution.

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 polyketone solution used for producing molded articles such as fibers and films of polyketone.

[0002]

2. Description of the Related Art Carbon monoxide and olefins such as ethylene and propylene are polymerized using a transition metal complex such as palladium or nickel as a catalyst, whereby carbon monoxide and the olefins are substantially completely alternately copolymerized. It is known that polyketones can be obtained (industrial materials, December issue, page 5, 1997). Many researchers have studied the application of polyketone as a fiber for industrial materials.Taking advantage of its high strength, high elastic modulus, heat resistance, dimensional stability at high temperatures, adhesiveness, and creep resistance, tire cords, belts, etc. Application to composite fiber such as reinforcing fiber and concrete reinforcing fiber is expected.

[0003] In particular, polyketones composed of ethylene and carbon monoxide (hereinafter abbreviated as "ECO") have high crystallinity and high melting point, so that fibers and films with high strength and high elastic modulus are most easily obtained, It is also the most excellent in thermal stability such as change in physical properties and small shrinkage. As a method for producing this ECO fiber, since melt spinning is difficult, ECO is dissolved in a solvent and fiberization is performed by a dry or wet spinning method. For example, JP-A-2-112413, JP-A-4-22
No. 8613, Japanese Unexamined Patent Publication No. 4-505344, etc., such as hexafluoroisopropanol,
m-cresol, chlorophenol, resorcin / water,
Organic solvents such as phenol / acetone, propylene carbonate / hydroquinone, pyrrole, resorcin / propylene carbonate, pyridine, formic acid, etc. can be used, but these solvents are expensive, highly toxic, or flammable. There is a problem in industrial use, such as the need to use a highly coagulant.

On the other hand, for example, International Patent Application No. 9
9/18143, Japanese Patent Application No. 11-72091, Japanese Patent Application No. 11-167370, and the like disclose that an aqueous solution of a zinc salt, a calcium salt, an iron salt or the like can be used as a solvent. These are low-toxic, nonflammable, inexpensive, excellent in spinning stability and solvent recovery, and are advantageous as industrial solvents. However, the method for producing a polyketone solution using a solvent in the latter patent document includes a method of adding a powdery polyketone to a solvent and stirring and dissolving the same, and a method of dissolving the polyketone solution under reduced pressure so that air bubbles do not enter the solution. It is only disclosed, and there is no disclosure regarding a technique of dissolving uniformly and at high speed.

[0005]

Problems to be Solved by the Invention For example, International Patent Application No. 99/18143, Japanese Patent Application No. 11-72091,
When a polyketone powder is prepared by dissolving a polyketone powder in an aqueous solution of a solvent such as a zinc salt, a calcium salt, an iron salt, etc., which is found in Japanese Patent Application No. 11-167370, the conventional method has poor solubility during dissolution. It was found that polyketone aggregates were easily formed. This is considered to be due to mixing the polyketone powder with the salt aqueous solution having a salt concentration of 60% by weight or more. In a salt aqueous solution having a salt concentration of 60% by weight or more, since the dissolution rate of the polymer is high, only the surface of the polyketone powder dissolves to form a film, thereby preventing the salt aqueous solution from penetrating into the polyketone powder.

When such polyketone powders come into contact with each other, large polyketone aggregates (so-called "mamako") are formed, and the salt aqueous solution hardly permeates into the inside. Once the polyketone aggregates are formed, it takes time to produce a homogeneous solution, which results in polymer modification and molecular weight reduction, causing problems. In particular, when a polyketone solution is produced using a high molecular weight polyketone, or when a highly concentrated polyketone solution is produced, this problem becomes remarkable. In the production of polyketone fibers used in the field of industrial materials such as tire cords requiring high strength and high elastic modulus, spinning stock solutions of high molecular weight polyketone are often used, and it is important to solve this problem. That is, an object of the present invention is to provide a method for producing a uniform polyketone solution at a high speed by suppressing the generation of polyketone aggregates when mixing the polyketone with the solvent.

[0007]

Means for Solving the Problems In order to solve the above problems, the present inventors have studied in detail a method for producing a polyketone solution. As a result, a zinc salt having a salt concentration of 0.01% by weight or more and 59% by weight or less is obtained. , A polyketone is dispersed in an aqueous solution containing at least one salt selected from calcium salts, thiocyanates, and iron salts to form a suspension. By adopting a method of separating and removing water from the suspension until the solvent uniformly penetrates into the polyketone powder, generation of polyketone aggregates is suppressed, and a uniform polyketone solution is produced at high speed. It has been found that this has become possible, and the present invention has been reached.

That is, the present invention relates to a polyketone in which at least 95 mol% of the repeating units are represented by the following structural formula (1) and at least one salt selected from the group consisting of zinc salts, calcium salts, thiocyanates and iron salts. In a method for producing a polyketone solution by dissolving in an aqueous solution containing
After dispersing the polyketone in an aqueous solution of the salt in an amount of not less than 01% by weight and not more than 59% by weight, a suspension is prepared.
It is another object of the present invention to provide a method for producing a polyketone solution, wherein water is separated and removed from the suspension until the content becomes 90% by weight or less.

[0009]

Embedded image In the polyketone used in the present invention, 95 mol% or more of the repeating unit is a polyketone represented by the above formula (1). In a range of less than 5 mol%, a repeating unit other than the above formula (1), for example, a unit represented by the following formula (2) may be contained.

[0010]

Embedded image Here, in the formula, R represents 1 to 30 organic groups other than ethylene, and examples thereof include propylene, butylene, and 1-phenylethylene. Some or all of these hydrogen atoms may be substituted with a halogen group, an ester group, an amide group, a hydroxyl group, or an ether group. Of course, R may be two or more types, and for example, propylene and 1-phenylethylene may be mixed. It is preferable that 97 mol% or more of the repeating unit is a polyketone represented by the above formula (1) from the viewpoint that high strength and high elastic modulus can be achieved and strength at high temperature and retention of elastic modulus are excellent. ,
Most preferably, it is 100 mol%.

Further, these polyketones may contain additives such as antioxidants, radical inhibitors, other polymers, matting agents, ultraviolet absorbers, flame retardants, metal soaps and the like, if necessary. . The intrinsic viscosity [η] of the polyketone used in the present invention is not particularly limited, but is preferably 2 dl / g or more from the viewpoint that a high-strength polyketone fiber can be obtained. However, if [η] is too large, the solubility and the spinnability tend to deteriorate, so it is preferably 20 dl / g or less. The range of [η] is more preferably 3 to 15 dl / g, and particularly preferably 4 to 10 dl / g.
dl / g.

The salt used in the present invention must be at least one salt selected from a zinc salt, a calcium salt, a thiocyanate and an iron salt. Specific examples of zinc salts include zinc chloride, zinc bromide, zinc iodide, zinc nitrate, zinc sulfate, zinc chlorite, zinc thiocyanate, and the like.Calcium salts include calcium bromide, calcium iodide And calcium chloride.Examples of the thiocyanate include zinc thiocyanate, aluminum thiocyanate, ammonium thiocyanate, calcium thiocyanate, potassium thiocyanate, magnesium thiocyanate, sodium thiocyanate, and barium thiocyanate. Examples of the iron salt include iron bromide, iron iodide, iron chloride and the like. Among these salts, zinc chloride, zinc bromide, zinc halides such as zinc iodide, and calcium bromide are preferred in terms of solubility of polyketone, cost of solvent, and stability of aqueous solution, and most preferably zinc chloride. is there. Also,
For the purpose of improving the solubility, reducing the cost, and stabilizing the polyketone solution, a plurality of the above salts may be mixed. In addition, a metal salt other than the above salts that is soluble in water may be mixed as long as the object of the present invention is not hindered.

Further, when a zinc halide is used,
Mixing the alkali metal halide or the alkaline earth metal salt is preferable in that the coloring of the polymer at the time of melting at a high temperature can be reduced or the solidification rate can be increased in the spinning step, and the spinning rate can be increased. Alkali metal halides and alkaline earth metal salts include sodium chloride, calcium chloride, lithium chloride, barium chloride, sodium bromide, calcium bromide,
Examples include lithium bromide, barium bromide, sodium iodide, calcium iodide, lithium iodide, barium iodide, and the like, with sodium chloride and calcium chloride being particularly preferred. Further, from the viewpoint of enhancing the stability at the time of dissolution or improving the spinnability, the weight ratio of the zinc halide to the alkali metal halide or the alkaline earth metal salt is preferably from 95/5 to 20/80, It is more preferably 90/10 to 30/70, particularly preferably 80/30.
20 to 40/60.

The water used for the aqueous solution of these salts is not particularly limited as long as it can be used industrially, and any water such as drinking water, river water, and ion-exchanged water can be used. Furthermore, methanol, ethanol, ethylene glycol, and the like are used within a range that does not impair the ability of the salt aqueous solution to dissolve the polyketone, usually within 30% by weight of water.
An organic solvent such as acetone, dimethylsulfoxide, N-methylpyrrolidone and the like may be contained.

The suspension of the present invention is prepared by dispersing the polyketone in the aqueous salt solution having a salt concentration of 0.01% by weight to 59% by weight. Here, the salt concentration is a value defined by the following equation. Salt concentration (% by weight) = [weight of salt / (weight of salt + weight of water)] × 100 A suspension is a state in which polyketone particles are not completely dissolved in the aqueous salt solution but are solid-liquid dispersed. Say. When the salt concentration is higher than 59% by weight, polyketone particles are aggregated when the polyketone is mixed and stirred in the salt aqueous solution, and a suspension cannot be formed. On the other hand, when the salt concentration is less than 0.01% by weight, it takes time to separate and remove water from the suspension, and the dissolution rate becomes slow. The preferred range is 1
To 50% by weight, more preferably 10%.
-40% by weight.

The shape of the polyketone is preferably powder because a uniform suspension can be easily obtained. The size of the powder, the longest part is 0.01 mm or more and 5 mm
The following is preferable in terms of dispersibility and permeability of the salt aqueous solution. The polymer ratio of the polyketone in the suspension varies depending on the salt concentration of the aqueous salt solution and the salt concentration and the polymer concentration of the polyketone solution to be produced. The amount is preferably 20% by weight or less because the operation of removing water from the suspension becomes difficult. The polymer ratio of the suspension is a value calculated by the following equation. Polymer ratio (% by weight) of suspension = [weight of polymer /
(Weight of polymer + weight of aqueous salt solution)] × 100

The polyketone solution can be produced by separating and removing water from the suspension thus obtained until the salt concentration becomes 60% by weight or more. Salt concentration is 6
Less than 0% by weight results in non-uniform dissolution and 90% by weight.
If it is higher, the solution becomes non-uniform due to salt precipitation or the like, resulting in an unsuitable polyketone solution for long-term stable spinning. From the viewpoint that a polyketone solution having a higher molecular weight and / or a higher polymer concentration can be produced, a preferable range of the salt concentration is 61 to 85% by weight. The preferred polymer concentration range of the polyketone solution produced as described above is 1 to 40% by weight. If it is less than 1% by weight, it is difficult to increase the spinning speed due to poor coagulation properties.
If the concentration is higher than 0% by weight, spinnability will be poor. further,
Preferably it is 3 to 30% by weight, most preferably 5 to 30% by weight.
20% by weight. Here, the polymer concentration is a value calculated by the following equation. Polymer concentration (% by weight) = [weight of polymer / (weight of polymer + weight of aqueous salt solution)] × 100

There is no particular limitation on the method of separating and removing water, a method of evaporating water by heating, a method of evaporating water under reduced pressure, a method of separating water using a reverse osmosis membrane,
Or a method combining these and the like can be mentioned. However, at a high temperature, the polyketone in the salt aqueous solution may be denatured or its molecular weight may be reduced. Therefore, a method capable of separating and removing water at a temperature as low as possible is preferable. From such a viewpoint, a method of evaporating water under reduced pressure or a method of separating water using a reverse osmosis membrane is preferable, and it is most preferable to evaporate water under reduced pressure in view of a concentration rate and simplicity of an apparatus. The reduced pressure condition is preferably from 0.1 to 750 torr, and preferably from 1 to 200 torr, from the viewpoint of apparatus cost and water evaporation efficiency.
r is more preferred. The temperature condition is preferably high in consideration of the evaporation efficiency of water, and is preferably low in consideration of denaturation of the polyketone and reduction in the molecular weight. A preferable temperature range is 0 to 200 ° C, more preferably 30 to 150 ° C, and particularly preferably 60 to 120 ° C. Spreading the suspension in the form of a film is preferred in that the evaporation rate of water is increased and the efficiency of separating water from the suspension is further improved.

When water is separated and removed from the suspension,
Stirring the suspension is preferred in terms of increasing the dissolution efficiency, and either a batch or continuous stirrer can be used. As the batch stirrer, a known stirrer having a single-shaft or two-shaft stirring blade and having excellent stirring efficiency can be applied.
As a single-screw stirrer, a stirrer having a spiral or double spiral blade is suitable. As the twin-screw agitator, for example, a planetary mixer, a double-arm kneader, a Banbury mixer, or the like using a hook having a rotation and a revolution as a stirring blade is applied. As a stirrer capable of continuously performing the supply of the suspension and the removal of the produced polyketone solution, for example, a screw extruder,
A co-kneader or a thin-film stirring type distillation machine is applied. It is preferable that all the stirrers have a high airtightness. Continuously supplying the suspension and taking out the polyketone solution using a continuous stirrer can reduce the difference in residence time from the production of the polyketone solution to spinning. This is preferable because the machine becomes compact. Further, among continuous agitators, a thin-film agitation type still is preferable in that the agitation can be performed while the suspension is formed into a film.

A method for producing a continuous type polyketone solution using a thin-film stirring type still will be described with reference to FIG. The suspension is adjusted in the slurry tank 2, and is quantitatively injected into the thin-film agitating type distillation machine from the suspension inlet 8 by the liquid sending pump 3.
It is possible to adjust the residence time in the thin-film stirring type distillation machine by this input amount. The residence time is preferably from 1 to 20 minutes, more preferably from 2 to 10 minutes. The introduced suspension is spread in the form of a film along the inner wall of the container by the distribution ring 7, and then stirred downward by the stirring blade 9 as shown in the sectional view, and moves downward. At this time, in the cylinder having the stirring blade, the temperature control and the pressure reduction control are performed, and the water gradually evaporates from the suspension and is removed from the steam discharge port 5. It is possible to control the evaporation rate of water vapor by adjusting the injection speed of the suspension, the temperature conditions, the pressure reduction conditions, and the rotation speed of the stirring blade, and to adjust the water concentration to a predetermined salt concentration until the suspension reaches the polyketone solution outlet 6. Is separated and removed to obtain a uniform polyketone solution.

[0021]

The present invention will be described in more detail with reference to the following examples, which do not limit the scope of the present invention. The measuring method of each measured value used in the description of the embodiment is as follows. (1) Intrinsic viscosity Intrinsic viscosity [η] was determined based on the following definition formula. T and T in the definition formula are 25 ° C. of a hexafluoroisopropanol solvent having a purity of 98% or more and a diluted solution of a polyketone dissolved in the hexafluoroisopropanol solvent.
Is the flow time of the viscosity tube at C is the solvent 10
The solute weight value in grams in 0 ml.

[0022]

Example 1 In a 500 ml separable flask, 300 g of an aqueous solution having a weight ratio of zinc chloride to sodium chloride = 65/10 and a salt concentration of 50% by weight, and intrinsic viscosity [η] = 3.
At 9 dl / g, substantially 100 mol% of the repeating unit was charged with 22.2 g (polymer ratio = 6.9% by weight) of a polyketone powder represented by the above formula (1), and was placed in an oil bath at a temperature of 50 ° C. The suspension was prepared by stirring and mixing with a helical blade for 5 minutes. Next, the temperature of the oil bath was raised while stirring,
When the temperature reached 00 ° C. (after 20 minutes), the degree of pressure reduction = 100
The pressure was reduced at torr, and water was removed from the suspension by evaporation. Sixty minutes after the oil bath temperature reached 100 ° C. (dissolution time), a polyketone solution having a salt concentration of 72.6% by weight and a polymer concentration of 9.7% by weight was obtained. The polyketone solution was uniformly transparent and pale yellow.

[0023]

Example 2 In a 500 ml separable flask, 300 g of an aqueous solution having a weight ratio of zinc chloride to sodium chloride = 65/10 and a salt concentration of 50% by weight and intrinsic viscosity [η] = 9.
At 9 dl / g, substantially 100 mol% of the repeating unit was charged with 10.5 g (polymer ratio = 3.4% by weight) of a polyketone powder represented by the above formula (1), and was placed in an oil bath at a temperature of 50 ° C. The suspension was prepared by stirring and mixing with a helical blade for 5 minutes. Next, the temperature of the oil bath was raised while stirring,
When the temperature reached 00 ° C. (after 20 minutes), the degree of pressure reduction = 100
The pressure was reduced at torr, and water was removed from the suspension by evaporation. 50 minutes after the temperature of the oil bath reached 100 ° C. (dissolution time), a polyketone solution having a salt concentration of 73.0% by weight and a polymer concentration of 4.9% by weight was obtained. The polyketone solution was uniformly transparent and almost colorless.

[0024]

Example 3 In a 500 ml separable flask, 350 g of an aqueous solution having a weight ratio of calcium chloride to zinc chloride = 38/24, salt concentration = 40% by weight, and intrinsic viscosity [η] = 3.
At 9 dl / g, substantially 100 mol% of the repeating unit was charged with 25.1 g (polymer ratio = 6.7% by weight) of a polyketone powder represented by the above formula (1), and was placed in an oil bath at a temperature of 50 ° C. The suspension was prepared by stirring and mixing with a helical blade for 5 minutes. Next, the temperature of the oil bath was raised while stirring,
When the temperature reached 00 ° C. (after 20 minutes), the degree of pressure reduction = 100
The pressure was reduced at torr, and water was removed from the suspension by evaporation. Seventy minutes after the temperature of the oil bath reached 100 ° C. (dissolution time), a polyketone solution having a salt concentration of 63.2% by weight and a polymer concentration of 10.2% by weight was obtained. The polyketone solution was uniformly transparent and light brown.

[0025]

Comparative Example 1 In a 500 ml separable flask, the weight ratio of zinc chloride to sodium chloride was 65/1 so that the composition of the polyketone solution obtained in Example 1 was the same.
0, 207 g of an aqueous solution having a salt concentration of 72.6% by weight, an intrinsic viscosity [η] of 3.9 dl / g and a substantially repeating unit 1
00 mol% of the polyketone powder 2 represented by the above formula (1)
2.2 g (polymer concentration = 9.7% by weight) was added, and the mixture was stirred and mixed with a helical blade for 5 minutes in an oil bath at a temperature of 50 ° C. Next, while stirring, the temperature of the oil bath was raised to 10
0 ° C. (after 20 minutes). Oil bath temperature is 100 ℃
Then, for 60 minutes (dissolution time), stirring was performed in a sealed state. The polyketone solution at this time was non-uniform with some white agglomerated particles and yellow.

[0026]

Comparative Example 2 In a 500 ml separable flask, the weight ratio of zinc chloride to sodium chloride was 65/1 so that the composition of the polyketone solution obtained in Example 2 was the same.
0, 205.5 g of an aqueous solution having a salt concentration of 73.0% by weight, an intrinsic viscosity [η] of 9.9 dl / g, and substantially 100 mol% of repeating units represented by the above formula (1). 5 g (polymer concentration = 4.9% by weight)
The mixture was stirred and mixed with a helical blade for 5 minutes in an oil bath at a temperature of 50 ° C. Next, the temperature of the oil bath was raised to 100 ° C. while stirring (after 20 minutes). Oil bath temperature is 10
Stirring was performed in a sealed state for 50 minutes (dissolution time) after the temperature reached 0 ° C. At this time, the polyketone solution was non-uniform with many white agglomerated particles and yellow. Table 1 summarizes the results of Examples 1 to 3 and Comparative Examples 1 and 2. Compared to the comparative example, it is possible to produce a uniform polyketone solution in a significantly shorter dissolution time, and the degree of yellowing is small.

[0027]

[Table 1]

[0028]

Example 4 A thin-film stirring type still as shown in FIG.
Inner diameter of agitator = 155mm, heated inner wall surface area = 0.2m
^{2. The} suspension was supplied and the polyketone solution was continuously taken out using Exeva (manufactured by Shinko Pantech Co., Ltd.) in which the distance between the stirring blade and the inner wall was 2 mm. In an aqueous solution having a weight ratio of zinc chloride to sodium chloride = 65/10 and a salt concentration of 30% by weight, intrinsic viscosity [η] = 5.9 dl / g, and substantially 100 mol% of the repeating unit is represented by the formula (1). The indicated polyketone powder was mixed in the slurry tank 2 so that the polymer ratio was 4.2% by weight, to prepare a suspension heated to 80 ° C. The suspension was continuously fed to the suspension inlet 8 at a rate of 45 kg / hour. The temperature of the heating jacket 4 was 100 ° C., the degree of pressure reduction was 100 torr, and the number of rotations of the stirring shaft was 500 rpm. The adjustment was performed, and a polyketone solution was continuously obtained from the polyketone solution outlet. At this time, the polyketone solution had a salt concentration of 73% by weight and a polymer concentration of 9.6% by weight, and was uniformly transparent and almost colorless.

[0029]

According to the present invention, when a polyketone is dissolved in an aqueous solution comprising at least one salt selected from a zinc salt, a calcium salt, a thiocyanate, and an iron salt, generation of polyketone aggregates is suppressed, and high-speed uniformity is achieved. It is possible to produce a suitable polyketone solution. In particular, the effect is great when producing a polyketone solution using a high molecular weight polyketone or when producing a high concentration polyketone solution.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view of a thin-film stirring type still and an enlarged sectional view taken along lines a and b.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor 2 Slurry tank 3 Liquid feed pump 4 Heating jacket 5 Steam outlet 6 Polyketone solution outlet 7 Distribution ring 8 Suspension inlet 9 Stirrer blade 10 Stirrer shaft 11 Film suspension

Claims (4)

[Claims] 1. At least 95 mol% of the repeating unit contains at least one salt selected from a zinc salt, a calcium salt, a thiocyanate and an iron salt of a polyketone represented by the following structural formula (1). In the method of preparing a polyketone solution by dissolving in an aqueous solution, the salt concentration is preferably 0.01% by weight or more.
After preparing the polyketone suspension by dispersing the polyketone in the aqueous salt solution of 9% by weight or less, separating and removing water from the suspension until the salt concentration becomes 60% by weight or more and 90% by weight or less. A method for producing a polyketone solution. Embedded image 2. The method for producing a polyketone solution according to claim 1, wherein the water is separated and removed from the polyketone suspension by evaporating the water under reduced pressure. 3. The method for producing a polyketone solution according to claim 1, wherein the polyketone suspension is spread in the form of a film, and water is separated and removed from the suspension. 4. The method for producing a polyketone solution according to claim 1, wherein the supply of the polyketone suspension and the removal of the polyketone solution are continuously performed.