JPH0622888B2 - Method for producing molded polyphosphazene - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a polyphosphazene molded article having improved mechanical properties.

More specifically, the present invention relates to a method for efficiently producing a polyphosphazene molded product having good mechanical and mechanical properties by performing a stretching heat treatment under specific conditions.

<Prior Art> Polyphosphazene has a main chain consisting only of an inorganic element and is extremely excellent in heat resistance and chemical resistance. Therefore, in recent years, polyphosphazene has been attracting interest as a plastics and an elastomer utilizing such characteristics. It is also well known that by appropriately selecting the side chain, polyphosphazene having various excellent properties such as abrasion resistance, oxidation resistance, water and oil repellency, low smoke generation, and biocompatibility can be obtained. There is.

It is also known to form a polyphosphazene having such excellent properties into a fibrous shape, a film shape or the like by, for example, wet molding. However, since these molded products obtained by the conventional methods are still insufficient in mechanical and mechanical properties, it is desired to further improve these properties.

<Object of the Invention> An object of the present invention is to provide a method capable of easily producing a polyphosphazene molded article having improved mechanical and mechanical properties from a commonly used polyphosphazene.
That is, just by stretching a polyphosphazene molded product as in the conventional method, the process stability at the time of stretching is deteriorated, or the mechanical properties of the resulting molded product are improved, but only a practically insufficient product is obtained. It has drawbacks such as not being possible.

The present invention is intended to provide a method for industrially obtaining a polyphosphazene molded article having good mechanical properties without such disadvantages.

<Structure of the Invention> As a result of intensive studies to achieve the above-mentioned object, the inventors have found that it can be easily achieved by stretching a polyphosphazene molded product in a specific temperature range and further heat-treating it in a specific temperature range. The present invention has been reached.

That is, the present invention mainly stretches a polyphosphazene molded article having a polyphosphazene consisting of repeating units represented by the following general formula (I) as a main constituent at a temperature within a range represented by the following formula (II), and then It is a method for producing a polyphosphazene molded article having excellent mechanical and mechanical properties, characterized by heat treatment at a temperature within the range represented by the formula (III).

Porphosphazene represented by the general formula (I) used in the present invention can be easily synthesized by a known method,
"Fiber and Industry", Vol. 38, No. 8, page 397, "Huain Chemical", Vol. 14, No. 6, page 22, etc. For example, polyphosphazene can be synthesized by the reaction represented by the following reaction formula.

(However, Ph is a phenyl group) In the present invention, examples of the polyphosphazene preferably used include the following.

(However, x + y = 2) (However, x + y = 2) Moreover, these copolymers may be used as long as they do not impair the mechanical properties, physicochemical properties, etc. required for the obtained molded product, and the side chain is a substituent of another kind. It may be the one exchanged in.

The weight average molecular weight of the polyphosphazene is preferably 50,000 or more, more preferably 100,000 or more. If it is smaller than this, the mechanical performance of the obtained molded product becomes extremely insufficient, which is not preferable.

It is also possible to use a mixture of two or more of the above polyphosphazenes.

Further, the polyphosphazene used in the present invention needs to have a transition temperature T (1) at which a crystalline state changes to a mesophase state and a transition temperature Tm at which a mesophase state changes to a melt state when measured by a differential calorimeter. The T
(1) Amorphous polyphosphazene having no Tm is not preferable because the resulting molded product has insufficient mechanical properties.

In the present invention, the term "molded product containing polyphosphazene as a main constituent component" means that at least 70% by weight or more, preferably 80% or more, of polyphosphazene is based on all polymer components.
It means that the content of the polyphosphazene is more than 1% by weight, and if it is less than this, the excellent various properties of polyphosphazene are weakened, which is not preferable.

In the present invention, the polyphosphazene molded product may have any form, and may have any form such as a fibrous form, a film form, a rod form, a sheet form, and a cylindrical form. However, the present invention cannot be applied to a molded product having a complicated shape that cannot be substantially stretched.

The polyphosphazene molded product before applying the stretching treatment and heat treatment of the present invention can be manufactured by a known method.
For example, a fibrous product can be easily obtained by extruding a concentrated solution of polyphosphazene from a nozzle, and a film or sheet can be easily obtained by extruding it from a slit.

Further, a polyphosphazene side chain having a small amount of a crosslinkable reactive group introduced thereinto may be used and then crosslinked during or after molding. Such reactive _{groups, -OCH 2 CH = CH 2,} -OC 6 H 4 -CH 2 CH = CH 2, Etc. can be given. A known method for reacting and cross-linking these reactive groups, for example, a method in which a radical generator such as a peroxide is kneaded, and cross-linking proceeds during molding,
Alternatively, a method such as heat treatment after molding or crosslinking by light irradiation can be applied. However, if the crosslinking proceeds too much,
It is not preferable because the effects of the stretching treatment and heat treatment of the present invention are reduced.

The polyphosphazene molded product used in the present invention may contain additives such as a colorant, an ultraviolet absorber, an antistatic agent, a heat deterioration inhibitor, a lubricant, and an inorganic filler in an appropriate ratio, if necessary. You can

The untreated molded product obtained by the above-mentioned method has a range represented by the formula (II), preferably T (1) -30 <Td <T (1) +10.
Is stretched at a temperature (Td) in the range. Here, the mesophase transition temperature T (1) is 10 ° C in a nitrogen atmosphere with a differential calorimeter.
This is the temperature of the endothermic peak that appears when the crystalline phase transitions to the mesophase phase, when measured at a heating rate of 1 / min. When the stretching temperature Td is lower than the above range, the molded product is not stably stretched, only voids are obtained, and the mechanical properties of the finally obtained molded product are insufficient, which is not preferable. On the other hand, if the stretching temperature Td is higher than this, it is considered that the orientation effect due to stretching does not appear, but this is not preferable because the mechanical properties become insufficient.

In the present invention, the stretching ratio is 0.5 to 0.95 times, preferably 0.6 to 0.9 times the maximum stretching ratio when measured at the stretching temperature.

In the present invention, the molded product stretched as described above is finally heat-treated within the temperature range (Th) represented by the formula (III). If the temperature is lower than this temperature range, sufficient improvement of mechanical properties cannot be obtained. On the other hand, if the temperature is higher than this temperature range, the molded product is softened and the mechanical properties of the molded product are conversely increased. It is not preferable because the characteristics are deteriorated. The heat treatment method may be either dry heat or wet heat, and the heat treatment stress may or may not be applied. It can be appropriately selected depending on the characteristics of the obtained polyphosphazene molded article.

<Effects of the Invention> As described above, according to the method of the present invention, a stretched and molded product having an advanced orientation can be obtained by stretching the polyphosphazene molded product within the specific temperature range. Also,
By further heat-treating this molded product within the above-mentioned specific temperature range, a molded product with further improved mechanical properties can be obtained.

The thus-obtained polyphosphazene molded article can be applied to a wide range of fields such as medical applications, electrical parts, and chemical industry fields under severe conditions depending on its properties.

<Example> Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to this. T in the examples
(1) is a Rigaku Denki DSC-10D differential calorimeter under nitrogen flow, 1
The temperature was measured at a temperature rising rate of 0 ° C./min, and the peak temperature of the endothermic peak was determined.

Example 1 Poly (bistrifluoroethoxyphosphazene) having an intrinsic viscosity of 0.52 when measured with an acetone solution at 25 ° C. was dissolved in acetone to prepare a 50 weight percent dope.
This was extruded into water to obtain a monofilament with a fineness of 700 de. The T (1) temperature of this product was 63 ° C. The results of stretching this unstretched monofilament at various temperatures are shown in Table 1.

From these results, it is found that when the temperature is within the temperature range of the present invention, the maximum draw ratio (DRmax) is large and the drawability is good, whereas when the temperature is out of this range, the DRmax is decreased and the drawability is poor. . The strength of the yarn obtained by drawing 0.75 times DRmax is also shown in Table 1. From these results, it can be seen that drawing in the temperature range of the present invention is also excellent in the physical properties of the drawn yarn. Is clear.

Of the stretched monofilaments that have undergone the above-mentioned stretching treatment,
Table 1 shows the results of heat treatment of a stretched monofilament having a stretch temperature of 60 ° C and a stretch ratio of 8.7 times under a tension using a hot plate.
2 shows.

When the heat treatment temperature is out of the range specified in the present invention, the strength of the monofilament yarn is hardly improved or, conversely, is decreased, whereas according to the present invention, the heat treatment effect is recognized and the strength is improved. You can see that

Example 2 Poly (bisphenoxypolyphosphazene) having an intrinsic viscosity of 2.75 measured at 25 ° C. in a tetrahydrofuran solution was compression-molded at 160 ° C. to obtain a sheet having a thickness of 1 mm. The mechanical properties of this product are breaking strength 0.9kg / m
m ² , rupture elongation of 185%, and T (1) temperature of 145 ° C
It was. When this sheet was stretched 3 times at 130 ° C. and then heat treated at 180 ° C. for 30 seconds without tension, the mechanical properties were a breaking strength of 1.6 kg / mm ² and a breaking elongation of 84%.

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Claims (1)

[Claims] 1. A polyphosphazene molded product containing polyphosphazene, which is mainly composed of a repeating unit represented by the following general formula (I), as a main constituent and stretched at a temperature (Td) within a range represented by the following formula (II). Processed, then below
A method for producing a polyphosphazene molded article having excellent mechanical and mechanical properties, which comprises heat-treating at a temperature (Th) within the range represented by the formula (III).