JPH0299611A - Production method for para-aromatic polyamide fibrously formed product - Google Patents

Abstract

PURPOSE:To facilitate the production of the title formed product of excellent heat resistance and mechanical properties by allowing a solution or a melt of para-aromatic dicarboxylic chloride to react with a solution of para-aromatic diamine using an wholly surface-renewable type of twin screw continuous kneader. CONSTITUTION:A solution or melt of para-aromatic dicarboxylic acid dichloride and a solution of aromatic diamine are continuously fed through continuous metering feeders into a mixer, then, the mixture is fed to a wholly surface- renewable type of twin screw continuous kneader, where the mixture is polymerized and solidified in the no-agitation and no-shearing zone, then polymerized and fibrillated with shearing and kneading forces in the paddle-arranged zone whereby the objective formed products suitable for a starting material of synthetic paper and a resin-reinforcing agent is obtained without the spinning process.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a fibrous para-aromatic polyamide molded product having excellent heat resistance and mechanical properties. The present invention relates to a method for producing a fibrous para-aromatic polyamide molded product suitable for use as a synthetic paper raw material, a resin reinforcing material, a friction material, etc., without going through a normal spinning process.

(Prior art) Conventionally, para-aromatic polyamides have poor heat resistance, mechanical properties,
It is known to be useful as short fibers and filaments with excellent electrical properties.

For example, Japanese Patent Publication No. 47-2489 describes high strength, high modulus fibers obtained from polyparaphenylene terephthalamide or copolymers thereof.

However, such high-strength, high-modulus fibers require special measures and equipment to be cut into short fibers, and are difficult to use as they are in fields such as synthetic paper raw materials and friction materials.

On the other hand, in JP-A-50-5980, a shearing force is applied by mechanical operation to a molded product having molecular orientation formed from an optically specific solution of a wholly aromatic polyamide, and the molded product is crushed into threads. A method for producing short fibers by fibrillation is described. However, in this method, the polymer obtained by polymerization is made into an optically anisotropic solution, which is then introduced into a coagulation bath to remove the solvent to produce a molded product, which is then crushed to form fibrillation. This makes the process complicated.

In addition, JP-A-61-19814 discloses that polymerization is carried out in a specially prepared polymerization solvent consisting of pyridine and an amide solvent, and the polymerization system is subjected to a mechanical parallel alignment treatment during the chain length growth in the polymerization system. , a method for producing polyparaphenylene terephthalamide short fibers is described. However, since this method requires the use of a multi-component solvent for polymerization, it has the disadvantage that the recovery operation when repurifying and recovering the polymerization solvent for use becomes complicated.

In addition, JP-A No. 63-112720 discloses solution polymerization of paraphenylenediamine and terephthalic acid chloride, and stirring is stopped just before solidification, and the surface of a solid reaction mixture mass is rubbed. A method of obtaining a fibrous material by scraping off the surface layer has been proposed. This method is
The biggest drawback is that it is basically a batch process and is inferior in industrial productivity.

(Problems to be Solved by the Invention) The purpose of the present invention is to industrially advantageously produce a fibrous para-aromatic polyamide molded product by simple operations without going through the traditional spinning process. It is in.

(Means for Solving the Problems) The present invention continuously supplies a solution or melt of a para-aromatic dicarboxylic acid chloride and a solution of a rose-based aromatic diamine to a mixer via a continuous quantitative feeder. In the continuous polymerization of para-aromatic polyamide, which is supplied and then the reaction is completed, a biaxial continuous kneader with a total surface renewal type is used as the polymerization device.
In addition, in the paddle arrangement of the continuous kneader, a non-stirring, non-shearing region is provided in the region where the reaction system solidifies to complete the assimilation, and then the reaction is completed while applying shearing action and kneading action. A method for producing a fibrous para-aromatic polyamide is provided.

In the present invention, "para-aromatic polyamide" refers to a polyamide in which an aromatic group in which a divalent bond is located is linked, and specifically, the aromatic group is a polyamide in which a divalent bond is located in one position.
, 4-phenylene (paraphenylene), 4,4'-biphenylene, 1,4-naphthylene, coaxially opposite direction from the aromatic ring, or 1,5-naphthylene and 2,6
- refers to aromatic groups such as those arranged in opposite directions along parallel axes, such as naphthylene. These aromatic groups may contain one or more lower alkyl groups such as methyl group and ethyl group, halogen groups such as methoxy group, ethoxy group, and chloro group.

Typical examples of these para-aromatic polyamides include boryvarahenzamide, poly-paraphenylene terephthalamide, poly-4,4' diaminenobenzanilitoterephthalamide, poly-IJ-N, N'-p -phenylene bis(p-benzamide) terephthalamide,
Poly-paraphenylene-2,6-naphthalamide, copoly-paraphenylene/4.4'-(3,3'-dimethylbiphenylene)-terephthalamide, poly-2-
Examples include chloro-paraphenylene terephthalamide. Among these, poly-paraphenylene terephthalamide or a copolymer in which 90 mol% or more of the repeating units constituting the polymer are paraphenylene terephthalamide units is preferred from the viewpoint of dimensional stability, heat resistance, and chemical resistance.

When carrying out continuous polymerization by the method of the present invention, first a solution or melt of a para-aromatic diamine (typically para-phenylene diamine) solution and a para-aromatic dicarboxylic acid chloride (typically terephthalic acid chloride) and separately.

The para-aromatic dimine solution is prepared by adding and dissolving a predetermined amount of para-aromatic diamine into a solution of a metal halide dissolved in an N-substituted amide type solvent.

The N-[converted amide type solvent mentioned here includes, for example, N-
Methyl-2-pyrrolidone, N,N-dimethylacetamide, N-acetyl-2-pyrrolidine, hexamethylphosphoramide, etc. are used, and N-methyl-2-pyrrolidone is especially used because of its low side reactions and safety to the human body. -Pyrrolidone is preferably used.

Metal halides are used as solubilization aids for para-aromatic polyamides, and include, for example, halides of alkali metals or alkaline earth metals, specifically LiC1.CaC1,z.

MgCf, etc. are used. Among these, LiCN-CaCj2z is preferably used in terms of solubility and effectiveness. The concentration of metal halide is preferably 1 to 10% by weight, more preferably 6 to 9% by weight. In addition, para-aromatic diamine solutions should be heated at -10°C to
It is preferable to store at 20°C, and the moisture content of the solvent used is preferably less than 200 ppm, and 50 ppm.
More preferably, it is n+ or less.

It is optimal for the metal halide mentioned above to be completely dissolved, but it can also be used even if it is dispersed in the form of a fine slurry.

On the other hand, para-aromatic dicarboxylic acid chlorides (e.g.
When using terephthalic acid dichloride as a solution, it is prepared in the same way as for para-aromatic diamines, and when used as a melt, it can be melted at 85 to 110°C without impairing the chemical activity of the element. It is maintained at a temperature close to its melting point and handled in an N2 sealed atmosphere. Further, since it is highly corrosive to metal materials such as stainless steel, it is preferable to use an apparatus in which the contact portion of the melt is lined with glass or fluororesin.

The melt or solution of the para-aromatic diamine solution and the para-aromatic dicarboxylic acid chloride thus prepared is supplied to the polymerization apparatus in the following manner.

First, the para-aromatic diamine solution is supplied to the mixer from a storage tank, through a continuous quantitative feeder, through a heat exchanger with a built-in line mixer, and after controlling the temperature at the mixer inlet.

On the other hand, the solution or melt of para-aromatic dicarboxylic acid chloride is directly supplied to the mixing device via a continuous quantitative feeder.

The term "continuous metering feeder" here refers to a device or system that can continuously supply a liquid to a mixer while accurately measuring the amount of liquid.General-purpose industrial metering feeders, such as plunger type diaphragm type, etc. Metering pumps, screw feeders, constant head pressure supply systems, etc. can be used.

When using a so-called metering pump, one of the preferred embodiments is to use a pulsating flow absorber or a so-called non-pulsation type pump in order to prevent or reduce pulsating flow of the pump.

In supplying each liquid, the molar ratio of para-aromatic dicarboxylic acid chloride and para-aromatic diamine is usually 1:1 (ie, equimolar). However, for reasons such as adjusting the degree of polymerization, the present invention will not be impaired even if one component is supplied in excess of about 1 mol % at most compared to the other.

The mixer here refers to a system that mixes a para-aromatic diamine solution and a para-aromatic dicarboxylic acid chloride solution or melt.
It is for continuous contact, dispersion and mixing, and is installed in close proximity to the polymerization equipment that will be installed later.

The function of the mixer is to have a jacket for heating or cooling, and to supply the para-aromatic diamine solution and the para-aromatic dicarboxylic acid chloride melt. When the linear velocity is 1, it is preferable that the feeding linear velocity of the para-aromatic dicarboxylic acid chloride melt can be 3 to 15. In addition, a structure in which the para-aromatic dicarboxylic acid chloride melt is supplied into the para-aromatic diamine solution is particularly preferable for producing a polymer with a high degree of polymerization with good operability. Furthermore, the residence time of the mixed liquid after injection and mixing is preferably short, and is usually set to 10 seconds or less, preferably 5 seconds or less.

The functions of the mixer have been described above, and these requirements are essential to prevent scaling, and are essential functions to stably and continuously supply both monomer liquids for a long period of time.

In addition to this mixer, there are also mixers with a structure that imparts high shearing force through high-speed stirring, such as the S-1 mixer, disper mill, and vibrine homo mixer, as disclosed in JP-A No. 53-138498. Not only does this complicate the device, but it also makes scaling more likely.
It should not be selected as a mixer.

The transfer force of reactants from the mixer to the polymerization machine is, for example,
The source can be found in the mixer itself, which is equipped with an inclined agitator or screw to provide extrusion capability, or it can be found in the indentation pressure of a continuous metering machine, the fall of its own weight, the withdrawal force of a polymerizer, etc. You can rely on it, or you can use both together.

The reactants discharged from the mixer are then transferred to the polymerizer.

The dispersion state of both liquids in the mixed liquid discharged from the mixer is insufficient to complete the reaction (so-called macro-mixed state).The dispersion state of this mixture is further increased to a micro-dispersed state. It is necessary to accelerate the reaction and subsequently apply a kneading action to increase the degree of polymerization by stirring and kneading until a solid substance in the form of powder or granules is obtained. What is preferably used as the polymerization apparatus is a so-called continuous biaxial kneader of the all-surface renewing type, which is disclosed in US Pat. No. 3,195,868, US Pat. No. 3,198,491, US Pat.

A continuous two-axis kneader with a full surface renewal type has a paddle with a convex lens-shaped or rice ball-shaped protrusion attached to two parallel axes. Both shafts rotate in the same direction while scraping the surface of the paddle, and the shearing force necessary to knead the reactants is generated between the paddles and between the paddle and the cylinder, while the transport force of the reactants is generated between the paddles and between the paddle and the cylinder. introduced a so-called screw unit, adopted an inclined paddle,
It can be generated by selecting the phase between adjacent paddles, etc., and the feeding force and torsion force can be freely generated by combining the rotating direction and these forces.

In the present invention, in such a system during polymerization, it is necessary to provide a non-agitation and non-shearing region in the solidification region. Here, solidification refers to a state in which the reaction system loses fluidity and the polymerization mixture begins to be pulverized if stirring is continued any further. The time required for solidification varies greatly depending on the polymerization conditions. In particular, it is greatly influenced by the monomer concentration and reaction initiation temperature (substantially equal to the temperature at the mixer inlet of the rose aromatic diamine solution).

In the continuous polymerization of the present invention, the upper concentration is usually 0.4 to 1.3.
It is a further feature of the present invention that continuous polymerization can be carried out at a high monomer concentration, which is industrially advantageous.

The purpose of kneading in the polymerization machine is to raise the degree of polymerization of the reactants to a desired level and complete the polymerization reaction. This corresponds to kneading the reactants until they form a powder or granular solid. At this time, the residence time in the polymerization machine, that is, the kneading time is usually 1 to 2
Selected within 0 minutes. In addition, as for the degree of adulteration,
One guideline is approximately 100 sec-' or more in terms of shear rate.

The temperature of the reactants in the mixer and in the polymerizer is approximately 80°C
It is preferable to do the following. This is because, at temperatures higher than 80°C, side reactions often occur which impede the obtaining of polymers with a high degree of polymerization.

In the present invention, providing a non-stirring, non-shearing region in the region where the reaction system is solidified in the paddle configuration of the all-surface renewing biaxial continuous kneader improves the molecular orientation and allows the reaction system to continue to solidify. It is essential for obtaining a fibrous polymer mixture by the applied shearing action and kneading action.

A non-stirring, non-shearing area can be created by inserting a cylindrical dummy paddle without a protrusion in place of the convex lens type or rice ball type paddle for kneading, but this method can be easily achieved. It can be said that it is a method that cannot be found. It is most important that the dummy paddle be inserted appropriately in the area where solidification occurs. In addition, it is desirable that the residence time in the non-stirring, non-shearing region be set in the range of 1 to 3 minutes, and the setting of the non-stirring, non-shearing region can be done in advance at the time of selecting polymerization conditions. Determine the position and retention amount and perform paddle formation.

In this way, the reactants solidified in the non-stirring, non-shearing area are sent to the paddle forming area, which is installed to provide shearing and kneading effects in the latter stage, by the screw paddles placed in the previous stage, and are sent to this area. The polymerization degree is increased and the reaction is completed while being made into fibers. At this time, the clearance between the paddle of the continuous kneader and the machine wall is preferably 1 mm to 5 mm. A clearance of 5 cylinders or more should not be selected because it becomes impossible to apply effective shear and therefore not only cannot increase the degree of polymerization, but also results in the formation of granular polymers. The most preferred embodiment is 1 to 2 m long.

Also, the circumferential speed of the paddle tip is 0.2 m/see.
The range of ~0.9 ta7sec is preferable, and more preferably 0.9 ta7sec.
．． A range of 3 m/sec - 0.7 m/sec can be said to be suitable.

The clearance effect and the effect of the peripheral speed are both substitutes for the shearing effect and the kneading effect, so in general, the peripheral speed of the paddle tip that is suitable for the clearance can be arbitrarily combined to obtain the desired fibrous material. Set conditions. This should be taken into consideration when controlling the morphology of the fibrous material by adjusting the shearing effect and kneading effect.

The fibrous polymer mixture thus obtained was washed with water,
In order to obtain a fibrous para-aromatic polyamide by neutralization and drying, a method commonly used for obtaining para-aromatic polyamide from a polymerization mixture of para-aromatic polyamide can be used.

The degree of polymerization of the fibrous material thus obtained varies depending on the reaction conditions, but it is preferably ηinh of 4.5 or more in terms of performance, and more preferably 5.0 or more.

This is because increasing the degree of polymerization directly leads to good mechanical properties.

The fibrous material obtained by the present invention has a length of 100 μm/~10 μm and a diameter of 5 to 100 μm, and has excellent thermal and mechanical properties, and can be used in the form of a strong sheet such as heat-resistant insulating paper. Can be formed into objects. Furthermore, it has high strength and modulus, and has a lower specific gravity than glass fiber, carbon fiber, or metal fiber, so it is useful for reinforcing resins and can also be used for R rubbing agents.

(Examples) Hereinafter, the present invention will be further explained with reference to Examples, but these Examples are not intended to limit the present invention in any way. The logarithmic viscosity (η1nh) as a guideline for the degree of polymerization shown in the examples is:
Concentration C = 0.5 g/d in 98.5% by weight concentrated sulfuric acid
Measurements were made using the solution in which the polymer was dissolved in step 1 at 35°C using a conventional method.

Example 1 In a dry stainless steel stirring tank with an internal volume of about 80 ffi,
60 kg of N-methyl-2-pyrrolidone purified by distillation was weighed and put therein, and then, while stirring, 5.77 kg of powdered anhydrous calcium chloride was precisely weighed and added, and dissolved at room temperature. After 2 hours had passed, 3.888 kg of powdered para-phenylenediamine was accurately weighed and added. (The ratio of calcium chloride concentration/polymer concentration at this time was 1.44.) After the addition, the mixture was stirred for about 1.5 hours. Next, tap water was poured into the jacket so that the temperature of the liquid in the stirring tank was about 20°C, and the mixture was cooled.

On the other hand, a lump of terephthalic acid chloride of about 8 kg was put into a stainless steel tank with an internal volume of about 151 which can pass 0.5 kg/crAG of water vapor through the jacket.
Steam was passed through and melted. In order to control the melt temperature, the stirrer was operated and the steam flow rate was adjusted to approximately 85±1.
It was kept in the ℃ range.

A plunger-type triple-type non-pulsating metering pump (
Manufacturer guaranteed accuracy ±0.1%) was used for each.

The polymerization equipment used was a mixer with a jacket through which warm water controlled at 9°C was flowed, and a Kurimoto Container Kneader #2 model (manufactured by Kurimoto Iron Works) as a kneading machine. installed.

The kneader has a clearance of 1.5 cylinders, and has a paddle arrangement that includes a screw-type paddle as the feeding area from the inlet, a convex lens-type paddle as the mixing area, a cylindrical gummy paddle as the non-stirring and non-shearing area, and a shearing and kneading area. As for the convex lens type paddle, the respective ratio is 1:2:2
:1. The paraphenylenediamine solution supply line was equipped with a jacket divided into three parts and a heat exchanger in which a static mixer was inserted inside the piping. The reason why the jacket is divided into three parts is to perform the minimum necessary heating or cooling corresponding to the set value of the supply amount of the individual phenylenediamine solution. On the other hand, the inner surface of the terephthalic acid chloride liquid delivery pipe was coated with Teflon, and the outer surface had a jacket structure, so-called double pipe.

When feeding the bulk phenylene diamine solution and the terephthalic acid chloride, the discharge amount of the metering pump was set to 10 for the former.
0cc/min (discharge linear velocity 5.09m/m1n), the latter is 9.08cc/min (discharge linear velocity 46.24m1n)
/win).

The retention amount in the mixer is approximately 5 cc, and the residence time is approximately 3 seconds.

By setting the conditions like this, the rotation speed of the kneader was set to 128 r.
When operation was started at pn+ (circumferential speed 0.33 m/sec), a viscous liquid initially flowed out from the outlet of the continuous kneader, but the viscosity soon began to increase and - for a moment, nothing came out. After about 3 minutes, a gel-like substance with almost no fluidity began to be discharged, which gradually turned into a powder-like substance, and then became fibrous and became stable.

At this time, the temperature of paraphenylenediamine at the inlet of the mixer was 11°C, and the temperature of the discharged fibrous polymer was 75°C.
It was °C.

This condition did not change even after approximately 3 hours of operation.

The discharged material from the kneader was sampled every 30 minutes, thoroughly washed with water, and then dried. The degree of polymerization (r) of the obtained polyparaphenylene terephthalamide fibers was 1nh.
) are 4.50.7.21.7.25.7.31.
7.35.7.32, and the fiber shape is fiber length 50
The fiber diameter was 0 μm to 100 μm, and the fiber diameter was about 60 μm.

After the operation was completed, the amount remaining in the kneader was weighed and found to be approximately 770 g, and the residence time was approximately 7 minutes.

Example 2 The weight of paraphenylenediamine in Example 1 was 4.104k.
g, the weight of calcium chloride was 6.216 kg, and the discharge amount of bulk phenylenediamine solution was 94.78 cc/mi.
The operation was carried out under exactly the same conditions and equipment, except that the

(The ratio of calcium chloride/polymer concentration at this time is 1.
It is 47. ) Approximately 6 minutes after the start of operation, a mixture of viscous liquid and powdery material came out, but after that, fibrous material was continuously discharged.

It was observed that this fibrous material was finer than that discharged in Example 1, and it was recognized that the shape of the fibrous material changed by increasing the polymer concentration. The operation was carried out for about 3.5 hours under these conditions, and as in Example 1, 30 hours of operation was carried out.
Sampling was carried out every minute, and as in Example 1, washing with water,
The degree of polymerization (η1nh) of the polyparaphenylene terephthalamide fibrous material obtained by drying was 8.62.8.4.
1.8. It was I8.8.12. The shape of the obtained fibrous material was such that the fiber length was 350 μm to 60 μm and the fiber diameter was 1
It was 0 μm to 80 μm.

(Comparative Example) The paddle configuration of the continuous kneader of Example 1 was changed from the inlet to a screw-type paddle as the feeding area, a convex-lens-type paddle as the mixing area, and a convex-lens-type paddle as the shearing and kneading area, each at a ratio of 1. :2
:3 ratio.

(This arrangement has no unstirred and unsheared areas.

)Other than this, operation was performed under exactly the same conditions. In this paddle knitting, the discharged material was turned into fine powder and the desired fibrous material could not be obtained.

The obtained degree of polymerization (771nh) was 8.73.8.54.
It was 8.40.8.68.8.62.

From Example 1.2 and Comparative Example, in the paddle configuration of the fully surface renewed biaxial continuous kneader, a non-stirring, non-shearing region was provided in the region where the reaction diameter solidified to complete the solidification, and then the shearing action was continued. It can be seen that by applying a kneading action, it becomes fibrous.

(Effects of the Invention) According to the method of the present invention, the continuous polymerization operation, which is an industrial polymerization method for para-aromatic polyamides, can be carried out at an economically advantageous high monomer concentration, and has a high degree of polymerization. Thermal
A fibrous para-aromatic polyamide with good mechanical properties can be obtained.

claimant Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] 1) A solution or melt of para-aromatic dicarboxylic acid chloride and a solution of para-aromatic diamine are each continuously supplied to a mixer via a continuous quantitative feeder, and then the reaction is completed. In the continuous polymerization of polyamide, a full surface renewing biaxial continuous kneader is used as the polymerization device, and in the paddle configuration of the continuous kneader, a non-stirring, non-shearing area is provided in the area where the reaction system solidifies. A method for producing a para-aromatic polyamide fibrous molded article, which comprises completing the reaction while subsequently applying shearing action and kneading action.