JPH0749528B2 - Polymer composite manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Fiber-reinforced plastics are regarded as important as load-bearing structural materials because of their dramatically improved physical properties, and various kinds of materials have been developed and put into practical use. The production of such a composite material requires a step of arranging separately produced reinforcing fibers in one direction and a step of further impregnating a matrix, and at that time, a complicated stepwise operation such as a step performed in an autoclave is included. Need.

On the other hand, the strength and durability of the composite material largely depend on the state of the interface between the reinforcing fiber and the matrix polymer. Since the fiber itself is a macro at the interface between the two, defects existing there propagate to the macro, leading to the destruction of the composite material.

In order to solve such a drawback, in place of the fibrous reinforcing material that can be dispersed only in a macro shape, a high modulus reinforcing polymer and a matrix polymer are dissolved in a common solvent, and both are micro-dispersed. Mix by molecular order and solidify /
It has been studied to produce a polymer composite in which the reinforcing polymer is dispersed and mixed in an extremely microscopic state by molding and the reinforcing polymer is oriented.

The present inventors have now used, as an organic polymer fiber, a polyazole-based polymer such as poly-p-phenylenebenzobisthiazole, which gives an excellent tensile modulus, as a reinforcing polymer, and in each combination system with various matrix polymers. We have been studying the high modulus of.

The inventors of the present invention previously used a high-modulus fiber by utilizing a liquid phase transition from an isotropic phase to an anisotropic phase of the polymer solution,
Proposed a method for obtaining a film (Japanese Patent Application No. 61-47191)
issue). However, in order to obtain a molded product in which a film of a polymer composite is laminated, it is advantageous in terms of formation to increase the thickness of the film, but in the above wet molding, increasing the thickness deteriorates the coagulation property. However, a good film could not be obtained.

In order to solve such a problem, the present inventors have used a polyazole-based polymer such as poly-p-phenylene benzobisthiazole as a reinforcing polymer and a flexible polymer as a matrix polymer. The present invention has been achieved as a result of intensive studies on the modulus and the film thickness.

That is, the present invention mainly comprises a reinforcing polymer (A) substantially composed of a polyazole having a rod-like skeleton and a matrix polymer (B) having a fusion property, and has a temperature range exhibiting optical pseudo-isotropy. And a temperature range exhibiting optical anisotropy, a polymer solution is extruded into a gas from a die or an orifice, then introduced into a coagulation bath, and then continuously taken out. In the manufacturing method, the temperature of the die or the orifice is maintained so that the polymer solution is in a temperature range in which the polymer solution exhibits optical pseudoisotropy, and the temperature of the coagulation bath is such that the polymer solution is optically pseudoisotropic. A method for producing a polymer composite, which is characterized in that the polymer composite is held so as to be in a temperature range exhibiting the property.

The reinforcing polymer (A) used in the present invention has the following formula [Wherein X is -S-, -O- or The bonds (a) and (b) are bonds that further form an azole ring or a hydrocarbon ring, or one of them has a hydrogen atom bonded thereto and the other has a bond. ] A substantially rod-like skeleton polyazole having an azole skeleton represented by
There are polymers described in the specification of No. 7,407, and polyazoles such as poly-p-phenylene benzobisthiazole, poly-p-phenylene benzoxazole, and poly-p-phenylene benzobisimidazole can be mentioned.

Regarding the molecular weight of the reinforcing polymer (A), the intrinsic viscosity which is a standard of the molecular weight is usually 2 or more, preferably 2.5 or more, particularly preferably 3 or more.

Matrix polymer (B) used in the present invention
Are soluble in the same solvent as the reinforcing polymer (A), and are aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 11; semi-aromatic polyamides such as polyhexamethylene isophthalamide; Aromatic polyamides such as polymetaphenylene isophthalamide; Flexible aromatic polyamides having flexible groups such as ether groups introduced;
Polyester; polycarbonate; polyvinyl acetate; polysulfone; polyether sulfone; polyether imide, polyether ketone; polyphenylene sulfide and the like.

The common solvent may be any solvent that can dissolve the constituent polymers, and examples thereof include acidic solvents such as concentrated sulfuric acid, methanesulfonic acid, chlorosulfonic acid, polyphosphoric acid, trifluoroacetic acid, and phosphoric acid. These may be appropriately mixed and used. Further, in order to suppress the hydrolysis of the dissolved polymer, an additive for reducing the amount of water in the solvent as much as possible may be mixed. Examples include addition of fuming sulfuric acid and chlorosulfonic acid.

A stock solution for forming a polymer complex is a polymer solution in which a reinforcing polymer and a matrix polymer are dissolved in the common solvent, and the polymer solution has a temperature range exhibiting optical pseudo-isotropicity,
A temperature range showing optical anisotropy is required.

The temperature range showing optical quasi-isotropy and the temperature range showing optical anisotropy vary depending on the type of polymer, the degree of polymerization, the component ratio and the concentration, but they can be determined by the following measurement methods. it can.

That is, prepare a predetermined polymer solution, spread it thinly on a slide glass and arrange it, and the thickness of the polymer solution is 0.1 mm.
And hold it in preparation. The sample thus prepared is placed under the observation of a polarizing microscope with crossed Nicols. First, the temperature of the sample is lowered to 0 ° C. to bring the polymer composite solution on the slide glass into a state exhibiting optical anisotropy.

When the temperature of the sample is gradually increased (5 ° C / min) while observing with a polarization microscope using a melting point measuring device (YANAGIMOTO Co., Ltd.), the visual field becomes dark at a specific temperature and becomes an optical isotropic state. It is observed that it has changed. The temperature at this time is named the transition temperature. After confirming that it became isotropic, the polymer solution on the slide glass is gradually cooled (2 ° C / min) from this temperature.

As a cooling method, a predetermined temperature change is obtained by mounting and controlling a cooling unit that causes a coolant to flow around the sample table. The cooling temperature is up to 0 ° C. When this sample is observed with a polarizing microscope having a crossed Nicols, the visual field image starts to become bright at a certain temperature as the temperature decreases. This temperature is called the pseudo-phase transition temperature.

The quasi phase transition temperature is lower than the phase transition temperature, and generally, the higher the phase transition temperature, the smaller the temperature difference between the phase transition temperature and the quasi phase transition temperature. The polymer solution having a phase transition temperature and a pseudo-phase transition temperature range once converted into the isotropic phase will be referred to as a pseudo-isotropic phase. Depending on the system, even if the phase transition temperature appears, it may not appear when the pseudo phase transition temperature is cooled to 0 ° C.

In such a system, it is shown that the pseudo isotropic region appears in the temperature range from the transition temperature to 0 ° C.

A film which is good in thickness can be obtained by extruding a pseudo-isotropic solution from a T-die into a coagulation bath maintained in the same pseudo-isotropic temperature range. A polymer composite solution obtained by dissolving component polymers in a solvent is heated from an optically anisotropic phase to an optically isotropic phase, and then cooled to a pseudo isotropic phase state. As a result, a good film can be obtained. This effect is small even if the temperature of the polymer complex solution after dissolution is raised between the quasi-isotropic transition temperature and the transition temperature.

In the method of the present invention, when the reinforcing polymer, the type of the matrix polymer, the molecular weight, the solvent system, and the component ratio / concentration of each polymer are determined, the optical pseudoisotropic property according to the above measurement method
Each temperature region showing optical anisotropy is measured, the temperature of the die or the orifice is kept in the optical pseudo isotropic temperature region, and the temperature of the coagulation bath is kept in the optical pseudo isotropic temperature region, respectively.
According to a known method, a polymer solution is extruded from a die or an orifice, introduced into a coagulation bath via a gas, and continuously taken out to produce a film or fiber semi-dry and semi-moist.

At this time, the quasi-isotropic polymer solution extruded from the die or the orifice is allowed to coagulate in the coagulation bath at the quasi-isotropic temperature. Therefore, it is considered that the reinforcing polymer further promotes the formation of rod-shaped aggregates as compared with the one solidified from an isotropic solution, and this dispersion is effective in improving the orientation by the subsequent stretching operation.

When the polymer solution is discharged from the T-die in the state of isotropic solution, a good film cannot be obtained. This is probably because the reinforcing polymer was dispersed in the microscopic state too much and did not give a good result to the orientation of the polymer by the subsequent stretching.

When the polymer solution is discharged from the T-die in the optically anisotropic state, the reinforcing polymer is excessively dispersed in the macro and the subsequent stretchability is poor and a good film cannot be obtained. The coagulation bath temperature is an important factor in bringing out the effect of the present invention. If the coagulation bath temperature is in the range below the pseudo-phase transition temperature, the polymer solution becomes coagulation temperature / humidity before the coagulation of the polymer solution discharged from the T die is completed during thick film formation. However, since the macrophase separation proceeds too much, a good film having excellent stretchability cannot be obtained.

The ratio of the reinforcing polymer (A) and the matrix polymer (B) used in the present invention is preferably such that A / A + B is in the range of 5 to 45%. When the reinforcing polymer (A) is less than 5%, the reinforcing effect is small, and when it exceeds 45%, the orientation of the reinforcing polymer (A) is lowered and the characteristics of the present invention cannot be exhibited.

The intrinsic viscosity used in the present invention is determined by a conventional method at 30 ° C. after dissolving in 100% sulfuric acid, methanesulfonic acid or chlorosulfonic acid so that the concentration of the reinforcing polymer (A) is 0.2 g / 100 cc. ηinh. When the reinforcing polymer (A) dissolves in any of the above solvents, the lowest value among them is taken as the intrinsic viscosity of the reinforcing polymer (A).

The effects of the present invention will be shown below with reference to examples, and the percentages in the examples are based on weight unless otherwise specified. fiber·
The mechanical properties of the film are 100% per minute for a sample length of 10 cm.
It was measured at the elongation rate of.

As a coagulation liquid for coagulating the polymer solution, a system in which a solvent used is mixed with an insoluble solvent, for example, an aqueous solution of sulfuric acid, an aqueous solution of methanesulfonic acid, an aqueous solution of phosphoric acid and the like can be mentioned.

The coagulation liquid may be two or more baths instead of a single bath. In this case, after the second bath, the tape, film and the like after the first bath are substantially solidified, and it is not necessary to satisfy the coagulation bath conditions of the present invention. The coagulation first bath must meet the conditions of the present invention.

The unstretched film that has just solidified needs to be neutralized with ammonia, sodium hydroxide or the like, especially in an acid solvent system, after the residual solvent is sufficiently removed.

The dry film becomes a high-modulus film by a normal stretching operation that is then used for stretching the film or the like.

Example 1 As a reinforcing polymer (A), poly-p-phenylenebenzobisthiazole (abbreviated as PPBT) was polymerized by a conventional method,
An intrinsic viscosity of 3.6 in a methanesulfonic acid solvent was obtained.

The matrix polymer (B) was prepared by adding 3,4'-diaminodiphenyl ether (50 mol%) and paraphenylenediamine (50 mol%) to N-methylpyrrolidone in a concentration of 6% under a dry nitrogen atmosphere. Dissolve in 5 ℃
After cooling to 50 ° C., terephthalic acid dichloride powder (100 mol%) was immediately added to the solution with vigorous stirring, and a polymerization reaction was carried out at 35 ° C. for 1 hour. It was Hereinafter, the polymer is abbreviated as PPOT-50.
Ηinh of PPOT-50 was 3.6 in sulfuric acid solvent. PPBT and PPOT
It was dissolved in methanesulfonic acid so that the component ratio of -50 would be 30/70 to prepare a polymer having a total concentration of 6%.
The temperature (phase transition temperature) at which the polymer composite solution transitions from anisotropy to isotropicity is 83 ° C. The quasi-phase transition temperature at which an anisotropic phase begins to appear upon cooling due to isotropicity was 42 ° C.

After heating the polymer composite solution to 85 ° C. which is higher than the phase transition temperature,
This was placed in a plunger maintained at 70 ° C. Connect the plunger and T-die with a pipe of about 30 cm,
The temperature of the pipe and the T-die was kept at 50 ° C between the pseudo-phase transition temperature and the phase transition temperature. The temperature of the polymer composite solution discharged from the T-die was 50 ° C.

The coagulation bath is a 60% aqueous solution of methanesulfonic acid and the temperature is 60 ° C.
Met. The film which started to coagulate was further dipped in a solution II containing 40% aqueous solution of 30% methanesulfonic acid and thoroughly washed with water. After neutralization with an aqueous sodium hydroxide solution, the mixture was washed with water for another 24 hours. Attach the Nagamaki tape to a rail-shaped fixing frame and allow it to dry for a fixed length, then use a hot air dryer to apply 15
It was dried at 0 ° C for 6 hours.

This sample was stretched at 390 ° C. on a hot plate at 0.8 times the maximum stretching ratio. The performance of the obtained sample is film thickness (μm) / modulus (GPa) / elongation (%) / strength (GPa) = 75/125 / 1.6
It was /1.3.

Example 2 As the reinforcing polymer (A), poly-p-phenylenebenzobisthiazole (PPBT) was polymerized in the same manner as in Example 1 to obtain an intrinsic viscosity of 5.4.

PPBT and PPOT-50 prepared in Example 1 were dissolved in methanesulfonic acid so that the component ratio was 25/75 to prepare a polymer having a total concentration of 5.7%. The phase transition temperature of the polymer composite solution was 85 ° C. The quasi-phase transition temperature was 50 ℃.

After heating the polymer solution to 85 ° C above the phase transition, heat it to 60 ° C.
Charged into the plunger held by. The temperature of the polymer composite solution discharged from the T-die was 60 ° C.

The coagulation liquid is a 60% aqueous solution of methanesulfonic acid, and the temperature is 60 ° C.
Met.

Other conditions are the same as in Example 1 and the film thickness (μm)
/ Modulus (GPa) / Elongation (%) / Strength (GPa) = 83/1
I got a film of 20 / 1.6 / 1.2.

Comparative Example 1 The polymer composite solution dissolved in methanesulfonic acid in Example 1 was heated to 45 ° C. below the transition temperature, and then treated with an aqueous solution of 60% methanesulfonic acid in a coagulation bath at a coagulation bath temperature of 45 ° C. It was discharged from the die to form a film.

After the film formation, the film was dried in the same manner as in Example 1 and then stretched at a maximum draw ratio of 0.8. The mechanical properties of the sample were as low as film thickness (μm) / modulus (GPa) / elongation (%) / strength (GPa) = 73/91 / 1.3 / 0.92.

Comparative Example 2 In Example 1, the temperature of the polymer solution dissolved in methanesulfonic acid was raised to 90 ° C., which is higher than the transition temperature, and then the temperature was maintained at that temperature from a T-die in a 60% aqueous solution of methanesulfonic acid. Extruded through the air layer.

The film after film formation was dried in the same manner as in Example 1 and then stretched at a maximum draw ratio of 0.8. The mechanical properties of the sample were inferior as film thickness (μm) / modulus (GPa) / elongation (%) / strength (GPa) = 71/81 / 1.1 / 0.95.

Claims (1)

[Claims] 1. A temperature range mainly containing a reinforcing polymer (A) substantially composed of a polyazole having a rod-like skeleton and a matrix polymer (B) having a fusion property and exhibiting optical pseudo-isotropic property. And a temperature range exhibiting optical anisotropy, a polymer solution is extruded into a gas from a die or an orifice, then introduced into a coagulation bath, and then continuously taken out. In the manufacturing method, the temperature of the die or the orifice is maintained so that the polymer solution is in a temperature range in which the polymer solution exhibits optical pseudoisotropy, and the temperature of the coagulation bath is such that the polymer solution is optically pseudoisotropic. A method for producing a polymer composite, characterized in that the polymer composite is held so as to be in a temperature range exhibiting properties.