JPH0637562B2 - Polymer composite manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field 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. However, there was a defect that the tensile modulus was lower than the expected additivity value when both polymer components were sufficiently oriented. Further, in order to obtain a molded product in which a film of a polymer composite is laminated, it is advantageous in terms of molding to increase the thickness of the film, but in conventional wet molding, increasing the thickness deteriorates coagulation properties. 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 provides a polymer solution mainly containing a reinforcing polymer (A) substantially made of polyazole having a rod-like skeleton and a matrix polymer (B) having a fusion property,
In a method for producing a polymer composite, which comprises casting on a substrate and then introducing it into a coagulation bath to form a film, a temperature range in which the polymer solution exhibits optical isotropy and an optical anisotropy are exhibited. And a temperature range exhibiting a property, the temperature of the polymer solution when cast on a substrate is within a temperature range exhibiting optical anisotropy,
After the casting, the polymer solution is introduced into the coagulating bath while transferring the apparent optical isotropy by heating the polymer solution.

The reinforcing polymer (A) used in the present invention has the following formula [Wherein, X represents -S-, -O- or -N-,
The bonds (a) and (b) are bonds that further form an azole ring or a hydrocarbon ring, or a hydrogen atom is bonded to one of them and the other is a bond. ] A substantially rod-like skeleton polyazole having an azole skeleton represented by
There are polymers described in 7,407, among which polyazoles such as poly-p-phenylenebenzobisthiazole, poly-p-phenylenebenzoxazole, and poly-p-phenylenebenzobisimidazole.

Regarding the molecular weight of the reinforcing polymer (A), the intrinsic viscosity which is a standard of the molecular weight is usually 1 or more, preferably 1.5 or more, particularly preferably 2 or more. On the other hand, those having an intrinsic viscosity that is too high are not preferable, and when the intrinsic viscosity is 30, good ones cannot be obtained.
In order to exert the effects of the present invention, the intrinsic viscosity of the reinforcing polymer is preferably 25 or less, particularly preferably 20 or less.

Matrix polymer (B) used in the present invention
Is a solvent that dissolves in the same solvent as the reinforcing polymer (A). Nylon 6, nylon 66, nylon 610, nylon 1
2, Nylon 11, etc. Aliphatic polyamides; Semi-aromatic polyamides such as polyhexamethylene isophthalamide; Aromatic polyamides such as polymetaphenylene isophthalamide; Flexible aromatic polyamides by introducing flexible groups such as ether groups; Polyesters; Polycarbonate; polyvinyl acetate; polysulfone; polyether sulfone; polyetherimide; polyether ketone; polyphenylene sulfide and the like.

The common solvent only needs to dissolve the constituent polymers, and examples thereof include acidic solvents such as concentrated sulfuric acid, methanesulfonic acid, chlorosulfonic acid, polyphosphoric acid, trifluoroacetic acid, phosphoric acid and the like. 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.

The 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 showing optical isotropy,
A temperature range showing optical anisotropy is required.

The temperature range showing optical isotropy and the temperature range showing optical anisotropy change depending on the type of the polymer, the degree of polymerization, the component ratio and the concentration, and can be determined by the following measuring methods. .

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 room temperature (20 ° C.) or lower to bring the polymer composite solution on the slide glass into a state exhibiting optical anisotropy.

Using a melting point measuring device (YANAGIMOTO CORPORATION),
Gradually increase the sample temperature (5
It is observed that the visual field became dark and changed to an optically isotropic state at a specific temperature when the temperature was increased by ° C / min.). The temperature at this time is named the transition temperature.

Apparent optical isotropic state means that when observing a predetermined polymer solution under a polarizing microscope, what initially had various shades of color changed to a uniform color, and the light gradually changed. Although the intensity decreases and becomes darker, it shows a state from the uniform color at this time until the intensity of the light gradually decreases to a constant darkness.

When this state is observed with the naked eye, it appears to be transparent and optically isotropic in appearance. Therefore, this state is called an apparent optical isotropic state.

The temperature range higher than the transition temperature is a temperature range showing optical isotropy, and the temperature range not reaching the transition temperature is a temperature range showing optical anisotropy.

When the concentration of the reinforcing polymer (A) in the solution is low, the polymer composite solution does not undergo a transition to optical anisotropy even at a temperature of 20 ° C. or less, and the optical isotropic property is obtained. Continue to hold. In a system in which such a transition to optical anisotropy does not occur, a good molded product cannot be obtained.
On the other hand, when the concentration of the reinforcing polymer (A) in the solution is high, the polymer composite solution does not undergo optical isotropic transition even at a temperature of 210 ° C. and has optical anisotropy. Continue to hold.

In such a system, the reinforcing polymer (A) and the matrix polymer (B) are remarkably decomposed in an acidic solvent, even if the solution becomes an isotropic solution when the temperature exceeds 210 ° C. Good molded products cannot be obtained.

In the method of the present invention, the types of the reinforcing polymer (A) and the matrix polymer (B), the intrinsic viscosity [η] or the characteristic viscosity ηinh, which is a standard of the molecular weight, the solvent and the component ratio and concentration of each polymer are determined. Then, the transition temperature from the optical anisotropy to the optical isotropy of the system is measured according to the above-mentioned measuring method, and the solution temperature at the time of casting is kept substantially below the transition temperature, and the polymer after casting The solution is heated above the transition temperature, transferred to an apparent isotropic solution, and then immersed in a coagulation bath. When the optically anisotropic solution is cast, the reinforcing polymer is microscopically phase-separated.

By heating this and bringing it into an isotropic state, the reinforcing polymer and the matrix polymer will dissolve into each other's phase, and the conditions for the reinforcing polymer to form extremely minute aggregates will be set. Presumed to be.

Contrary to this, a polymer solution which is heated to a temperature not lower than the transition temperature to become optically isotropic is cast on a heated substrate, and then the solidified product has poor stretchability and good mechanical properties. Not shown. Immediately prior to coagulation, the method of the present invention and the casting method in the isotropic solution described above appear to be similar, but
The resulting mechanical properties of the film show a significant difference. The reason for this is not clear, but in the case of casting in an anisotropic solution as in the present invention and then heating to an isotropic solution, microdispersion of the reinforcing polymer into the matrix polymer is more effective. It seems that it is dispersed in a form that is easy to do.

As a molding method, casting may be performed on a hard substrate such as a glass plate or a metal plate, or may be cast on a soft substrate such as a cloth.

As a continuous film forming method, a polymer solution extruded from a T-die or the like is cast onto a substrate such as a belt in an optically anisotropic state, and then heated with hot air or a heater to produce an apparent optical The film can be formed by bringing it into a state of isotropicity and immersing it in a coagulating liquid.

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 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.

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. It is ηinh. When the reinforcing polymer (A) dissolves in any of the above solvents, the lowest value among them is 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 measured with a sample length of 4 cm at an elongation rate of 10% per minute.

Example 1 As a reinforcing polymer (A), poly-p-phenylenebenzobisthiazole (abbreviated as PPBT) was polymerized by a conventional method to obtain a polymer having an intrinsic viscosity of 4.1 in a methanesulfonic acid solvent.

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., the solution of 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 a sulfuric acid solvent. P
Dissolved in methanesulfonic acid so that the ratio of PBT and PPOT-50 was 30/70, and the total polymer concentration was 6%.
Created one. The temperature (phase transition temperature) at which the polymer complex solution undergoes isotropic transition from anisotropy was 65 ° C.

The polymer solution was cast on a glass substrate at room temperature using a doctor knife (slit width 100 μm). It was placed on a heating plate and the temperature was raised to 80 ° C. The polymer solution was immersed in the coagulation liquid while the intensity of light gradually decreased from the uniform brightness in the observation of crossed Nichols.

An 80% aqueous solution of methanesulfonic acid was used as the coagulating liquid. The coagulated film was thoroughly washed with water, neutralized with an aqueous sodium hydroxide solution, and then washed with water for another 24 hours. The film was placed in a fixed frame, naturally dried, and then stretched at a temperature of 350 ° C. and 470 ° C. to obtain a stretched uniaxially oriented film at a draw ratio obtained by multiplying the maximum draw ratio by 0.8.

The mechanical properties of the film are: film thickness (μm) / modulus (GPa) / elongation (%) / strength (GPa) = 65/113
It was /1.2/1.0.

Examples 2 to 4 In Example 1, the slit width of the doctor knife was 2000.
Films were formed under the same conditions except that the thickness was changed to μm, 4000 μm, and 5000 μm to obtain a uniaxially oriented film.

The mechanical properties of the film were as shown in Table 1 and good ones were obtained.

Comparative Examples 1 and 2 PPBT / PPOT prepared in the same manner as in Example 1
Put the polymer solution of -50 in a glass container kept at a temperature of 80 ° C, mix and heat for about 20 minutes, and after confirming that the polymer solution is optically isotropic, keep it at 80 ° C. It was cast on a substrate with a doctor knife of 1000 μm and 2000 μm. It was placed in a coagulation bath and the subsequent drying was the same as in Example 1.

The mechanical properties of the uniaxially oriented film are as follows: Doctor Knife 10
Film thickness (μm) / modulus (GP) from 00μm
a) / elongation (%) / strength (GPa) = 65/85 / 2.1 / 1.2.

The film cast from a doctor knife of 2000 μm had a large number of Maltese crosses in the solidified film and was poorly stretched.

Claims (1)

[Claims] 1. A polymer solution 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 is cast on a substrate. Then, in a method for producing a polymer composite, which comprises introducing into a coagulation bath to form a film, a temperature range in which the polymer solution exhibits optical isotropy and a temperature range in which optical anisotropy is exhibited. The temperature of the polymer solution at the time of casting on the substrate is within a temperature range showing optical anisotropy, and after casting, the polymer solution is heated to give an apparent optical effect. A method for producing a polymer composite, which comprises introducing a film into a coagulation bath while transferring it isotropically to form a film.