KR920009693B1 - Aromatic polyester with softness side chain and process for preparing thereof - Google Patents

Abstract

The whole aromatic polyester comprises the aromatic diol derivative of formula (I) and the same equivalent 2,5-dialkoxy terephthalate, and has 0.15-2.51 dl/g of inherent viscosity (7 inh), and its decomposition starts at 275-326 deg.C. In the formula, R is CnH2n+1 (n = 8, 12 or 16); Ar is (II), (III), (IV), (V) or (VI). Pref. the amt. of the full aromatic polyester is reduced by 5 % at 350-392 deg.C, and the whole aromatic polyester is easy disolved in THF, DMF or CHCl3.

Description

Wholly aromatic polyester having a flexible side chain and a method of manufacturing the same

1 is an IR spectrum of a wholly aromatic polyester having 12 carbon atoms in the side chain.

2 is a ¹ H-NMR spectrum of a wholly aromatic polyester having 12 carbon atoms in the side chain.

3 is a DSC curve of a wholly aromatic polyester having 12 carbon atoms in the side chain.

4 is a TGA curve of a wholly aromatic polyester having 12 carbon atoms in the side chain.

5 is a polarized light micrograph (magnification 100 times) of P-HQ-12.

6 is a polarized light micrograph (magnification 100 times) of P-BP-12.

7 is an X-ray diffraction curve of P-HQ-12, P-BP-12 and P-ND-12.

FIG. 8 shows the molecular backbone structure of a wholly aromatic polyester with flexible side chains.

9 is a graph showing the relationship between the carbon number (n) of the alkoxy side chain and the distance (l) between the polymer skeletons obtained in the X-ray diffraction curve.

The present invention relates to a wholly aromatic polyester having a flexible side chain and a method for preparing the same, and more particularly to a processable wholly aromatic polyester which is a new type of liquid crystal polymer composed of an aromatic diol derivative and a 2,5-dialkoxy terephthalate, and It relates to a manufacturing method thereof.

A wholly aromatic polyester of thermotropic liquid crystal can produce fibers or plastics having high strength and high modulus by spinning or forming in liquid crystal state. It is also actively underway.

Among these wholly aromatic polyesters, poly (P-phenylene terephthalic acid), which has a simple structure and can be expected to have the greatest strength, has a high Tg (267 ° C) and Tm (467 ° C), making it impossible to make a fiber or plastic product therefrom. have.

In addition, poly (P-hydroxybenzoic acid) also melts with decomposition near 500 ° C and shows only solid-solid phase transitions between 325 ° C and 360 ° C, making it impossible to mold under normal processing conditions. Special processing techniques, such as compression or sintering methods, must be used.

In recent years, regularity of repeating units of polymers or insertion of nonlinear structures that break the linearity of flexible spacers or chains in main chains by lowering the melting point and increasing the solubility in order to enhance the processability of rigid polymers. A wide range of polymer design concepts have been created and studied, including copolymerization methods to break the benzene ring and introducing substituents into the benzene ring (see HF Kuhfuss and WJJackson, Jr. (East-man Kodak), US Pat. 3,778,410 (1973)

In the mid-1980s, Lenz et al. And Ballauff studied how to reduce the melting point of polymers by combining flexible chains on the side of rod-type wholly aromatic polyesters. Particularly, Ballauff, based on Flory's lattice model, predicted the appearance of liquid crystal phases. Rationalized. (See J. Majnusz and R. W. Lenz, Eur. Polym. J. 21,565 (1985); M. Balauff, Makromol. Chem. Rapid Commun. 7,407 (1986))

However, these conventional techniques are only presented as academic theory, and there is still much room for improvement in order to use these techniques industrially.

Therefore, in the present invention, by introducing a flexible side chain to the wholly aromatic polyester in order to make industrial use of the wholly aromatic polyester showing high strength and high modulus of elasticity, the workability is greatly improved while showing the characteristics of low melting point and solid solubility. It is an object of the present invention to provide a new type of wholly aromatic polyester and a method for producing the same.

Hereinafter, the present invention will be described in detail.

The present invention consists of an aromatic diol derivative represented by the following structural formula (I) and the same equivalent of 2,5-dialkoxy terephthalate, having an intrinsic viscosity (ninh) of 0.15-2.51 dl / g and of 275 ° C-326 ° C. It is a wholly aromatic polyester which specifies that decomposition starts at temperature.

Wherein R is C _n H _{2n + 1} (n = 8,12 or 16), and Ar is

to be.

Hereinafter, the present invention will be described in more detail.

The wholly aromatic polyester according to the present invention is prepared by polymerizing the aromatic diol derivative represented by the above formula (I) with 2,5-dialkoxy terephthalic acid chloride, wherein the monomer 2,5-dialkoxy terephthalic acid chloride is as follows. Prepared in the same way.

Synthesis of Monomer

First, by combining alkyl bromide with a hydroxy group of diethyl-2,5-dihydroxy terephthalate to synthesize 2,5-dialkoxyterephthalate and saponification to form 2,5-diakoxyterephthalate This is chlorinated with thionyl chloride to give 2,5-dialkoxy terephthalic acid chloride.

After the monomer is synthesized in this way, it is polymerized with an aromatic diol derivative. There are three polymerization methods that can be used in the present invention.

end. First solution polymerization method (method A)

Using pyridine as a solvent, aromatic diols and the same amount of 2,5-dialkoxy terephthalic acid chloride are mixed and the mixture is allowed to react at a temperature of 70 ° C-90 ° C for 3-5 hours.

I. Second solution polymerization method (method B)

In tetrachloroethane, aromatic diol and the same equivalent of 2,5-dialkoxy terephthalic acid chloride are dissolved, and pyridine is added thereto at room temperature under a nitrogen stream, and the mixture is then heated at a temperature of 90 ° C-100 ° C to 3-5 ° C. React for hours.

All. Melt polymerization method (method C)

Melt-reacts the aromatic diol and 2,5-dialkoxy terephthalic acid chloride at a temperature of 100 ° C, and as the viscosity increases while injecting dry nitrogen, the reaction temperature is increased to 4-6 until the temperature reaches 250 ° C-270 ° C. Allow to warm up for time.

In the present invention, in naming the aromatic diol derivative of the structural formula (I), it will be named as follows according to the type of the substituent Ar.

이면 HQ-n이라 한다.That is, Ar

Is called HQ-n.

이면 DPB-n이라 한다.Ar is

If it is called DPB-n.

이면 BP-n이라 한다.Ar is

If it is called BP-n.

이면 DDPSO-n이라 한다.Ar is

Is called DDPSO-n.

이면 ND-n이라 한다. (여기서, n은 8, 12 또는 16이다)Ar is

It is called ND-n. Where n is 8, 12, or 16

Hereinafter, examples of the present invention will be described.

Examples 1-3 (Method A)

To 1.3 g (0.11 mole) of cooled thionyl chloride in an iced water container, 10 ml of pyridine was slowly added while maintaining at a low temperature, followed by stirring for 30 minutes.

A solution of 2.1 g (0.005 mole) of 2,5-diol cocciterephthalic acid in 10 ml of pyridine was added to the mixture over 20 minutes and maintained at room temperature for 20 minutes.

Subsequently, an equivalent amount of aromatic diol (Example 1; HQ-8, Example 2; BP-8, Example 3; ND-8) dissolved in 10 ml of pyridine was added at once and the mixture was reacted at 80 ° C. for 4 hours. I was.

Methanol was poured into the reaction product solution having a viscosity, and the precipitate was collected and filtered. The resultant was washed with warm methanol and dried in a vacuum dryer at 100 ° C. to obtain a polymer.

Examples 4 to 9 (Method B)

Aromatic diols equivalent to 2 g (0.0035 mole) of 2.5-alkoxyterephthalate chloride (Example 4; BP-12, Example 5; ND-12, Example 6; DBP-12, Example 7; DDPSO-12, Example 8 BP-16, Example 9 ND-16) was dissolved in 11 ml of tetrachloroethane and 1.1 g of pyridine was slowly added at room temperature under a stream of nitrogen with vigorous stirring.

The mixture was warmed to 100 ° C. and stirred for 4 hours, and then distilled off to twice the volume of solvent used to catch precipitation with excess methanol.

After filtration and washing with methanol, the resultant was dried in a vacuum dryer at 100 DEG C for 24 hours to obtain a desired polymer.

[Examples 10 to 12 (Method C)]

2.5- dialkoxy terephthalic acid chloride and aromatic diol (Example 10; HQ-12, Example 11; BP-12, Example 12; ND-12) were reacted at 100 占 폚 with stirring.

HCl generated at this time was removed by continuously flowing dry nitrogen into the reaction vessel. As the reaction proceeds, the viscosity increases and the stirring becomes difficult, and the reaction is carried out for 5 hours while gradually increasing the temperature from 250 ° C to 270 ° C depending on the polymer. When stirring was no longer difficult, the reaction was stopped to obtain a polymer.

The polymerization conditions and yields of the aromatic polyesters prepared according to Examples 1 to 12 are shown in Table 1 below.

TABLE 1

* In the polymer column of Table 1, P- means a polymer. That is, P-HQ-8 refers to an wholly aromatic polyester prepared using HQ-8 as an aromatic diol.

The wholly aromatic polyester according to the present invention has the following characteristics.

[Molecular Structure]

Geotinde drawings accompanying the turning 1 showing the IR- spectrum of the wholly aromatic polyester is typically in the side chain of the polymer having a carbon number of 12 according to the present invention, the absorption band of the carbonyl group by a polymerization reaction at 1750cm ^-1 and 1720cm ^-1 you can see the absorption band of the aryl ether vibration due to CO stretching vibration alkoxy groups attached at 1000-1300cm ^-1, and the benzene ring at 1040cm ^-1 and 1250cm ^-1.

Figure 2 also shows the ¹ H-NMR spectrum of the polymers, the signal of -OCH ₂ (CH ₂ ) ₁₀ CH ₃ at δ 0.75-0.99ppm, the signal of -OCH ₂ (CH ₂ ) ₁₀ CH ₃ is δ 1.00 At -2.50 ppm, the signal of -OCH2 (CH2) 10CH3 can be seen at δ 3.80-4.20 ppm and the signal of Ar-H at δ 7.00-8.50 ppm, thus revealing the structure of the desired polymer.

1 and 2, a) shows a spectrum of P-BP-12, b) P-ND-12, c) P-DBP-12 and d) P-DDPSO-12.

[Solubility]

Table 2 shows the solubility test results of the wholly aromatic polyester according to the present invention.

In general, rod-shaped wholly aromatic polyesters are known to dissolve only in strong acids such as sulfuric acid without being soluble in a general organic solvent.

However, the wholly aromatic polyester incorporating the side chain according to the present invention was partially or completely dissolved in a solvent such as THF, DMF, CHCl ₃ and the like.

The partially soluble polymer here is believed to be due to the high molecular weight portions of the rod polyester obtained by melt polymerization.

And, when CO or SO ₂ were inserted between the benzene rings of the diols, the polymers were more easily dissolved.

As the flexible side chain is introduced into the wholly aromatic polymer chain as described above, the solubility thereof is rapidly increased, and thus the film can be easily formed by solvent casting.

TABLE 2

In Table 2, ○ represents dissolution under heating,? Represents partial dissolution under heating, and × represents insolubility.

Thermal Analysis and Solution Viscosity

Among the polymers synthesized according to the present invention, the results of thermal and thermal stability by DSC and TGA of polyesters having 12 carbon atoms in the side chain are shown in FIGS. 3 and 4, respectively.

The DSC curve of FIG. 3 shows that P-HQ-12 and P-BP-12 have three endothermic peaks at different temperature ranges.

The melting point of the peak side chain (Ts) at the lowest temperature and the peak at the highest temperature correspond to the temperature (Ti) transition to the isotropic liquid and the peak observed at the midrange temperature is the transition to the mesophase. It can be seen as the temperature Tt.

As will be described later, the optical structure of the polarizing microscope showed a liquid crystal phase, and Tt in the DSC phase was reversibly shown during heating and cooling, thereby confirming that it was an enantiotropic liquid crystal.

P-ND-12 showed a transition temperature between Ts and Ti, so it was expected to appear in the liquid crystal phase, but no optical structure was found.

This is believed to be because the 1.5-naphthalene unit interfered with the liquid crystal phase formation by destroying the linear structure of the polymer.

DSC curves of P-DBP-12 and P-DPPSO-12 also showed endothermic peaks presumed to be phase transitions between Ts and solids at the first heating.

However, in these polymers, it is considered that Ti is not observed and does not show crystallinity in the polymer itself skeleton except for the side chain which crystallizes. In particular, no phase transition could be observed during cooling or secondary heating on the DSC curve. From this thermal behavior, it can be inferred that the molten side chains maintained an disordered molecular arrangement during primary heating, resulting in an amorphous polymer. .

A simple evidence supporting this result is that the polymer obtained by cooling after primary heating is transparent.

Table 3 shows the analysis results and solution viscosity of the polymers according to the present invention.

TABLE 3

1. Ts: melting point of the side chain.

2. Tt: The temperature at which the transition to the meso phase.

3. Ti: The temperature at which an isotropic liquid is transferred.

4. Tid: Initial decomposition temperature.

5. ηinh: Intrinsic viscosity.

In Table 3, the melting point of the wholly aromatic polyester having no side chain was known to be around 500 ° C., but it was confirmed that the melting point could be considerably lowered to 149 ° C.-292 ° C. depending on the length of the chain.

Polymers with 12 and 16 carbons in the side chains showed endothermic peaks at 70 ° C or lower due to the melting of them, and the melting point increased as the carbon number in the side chains increased.

The phase transitions between solids were several depending on the polymer, and the temperature at which the liquid crystal phase appeared in the case of P-HQ and P-BP was greatly influenced by the length and molecular weight of the side chain.

According to the TGA analysis, depending on the polymer, pyrolysis began in the region of 275 ℃ -326 ℃ and weight loss of 5% occurred at 350 ℃ -392 ℃, indicating relatively high thermal stability.

When the intrinsic viscosity of the polymers is measured, the synthesized by melt polymerization generally has a large value, especially P-BP-12 is 1.09 dl / g in the case of a solution polymer, while the molten polymer is 2.51 dl / g, more than twice as large as the viscosity value. Seemed.

[Polarization microscope]

FIG. 5 is a polarized light micrograph of P-HQ-12 obtained at 190 ° C., and FIG. 6 obtained of P-BP-12 at 200 ° C.

All of them show a marble or schlieren structure that can be regarded as a nematic tack, especially when annealing P-BP-12 at 200 ° C for 45 minutes.

However, P-ND-n, P-DBP-n and P-DDPSO-n did not observe any optical structure related to liquid crystal.

This is believed to be due to the breakage of the straight chain of the polymer chain by the use of 1,5-naphthalenediol when the polymer backbone serving as the mesogenic unit is P-ND-n and for the other two polymers. It is believed that CO and SO ₂ are not present in the mesogen unit, which interferes with the arrangement of adjacent chains and thus has no liquid crystallinity.

[X-ray analysis]

Wide angle X-ray scattering experiments were performed to investigate the structure of the polymer in the solid state.

7 shows the X-ray diffraction curves of P-HQ-12, P-BP-12 and P-ND-12. The general diffraction curve shows that the above three polymers have high crystallinity.

The relatively sharp diffraction curve in the lowest angle region of this curve is determined as the distance between the skeletons of the hard polymer due to the side chain (L) as shown in FIG.

Since the number of carbon atoms in the zigzag alkoxy side chain in this polymer is 12, the total length is 15.24 Å, considering that the length per unit of CH ₂ is 1.27 Å.

However, the actual measurement distance between the polymer backbones is 20.33Å for P-HQ-12 and 22.53Å for P-BP-12, so it can be expected that the diameter of the polyester skeleton including oxygen atoms will be 5.09Å and 7.29Å, respectively.

Therefore, the distance between the skeleton of the polymer having octyloxy and hexadecyloxy substituent based on the polymer having dodecyloxy substituent can be estimated and confirmed from the actual X-ray diffraction analysis.

On the other hand, Table 4 below shows the measured 2θ values of P-HQ-n and P-BP-n (n + 8,12,16) and the d value calculated using Bragg's law from them. .

In FIG. 9, as the length of the side chain decreases or increases, the distance between the polymer backbones increases proportionally, indicating that the polymer is linear and crystallized in a layered structure.

Here, when n = 0, the contact point was an average diameter of the skeleton, with 5.20 kPa of P-HQ-n and 7.58 kPa of P-BP-n.

TABLE 4

* s: strong, m: medium, w: weak, vw: very weak, b: gentle.

According to the present invention, the characteristics of the polymer in which the flexible side chain is introduced into the wholly aromatic polyester are as follows.

1. The wholly aromatic polyester substituted by the flexible side chain was significantly dissolved in solvents such as P-chlorophenol, THF, DMF, CHCl ₃ and so on, compared to the polymer itself without substituents.

2. The melting point (Ts) of the polymer side chain increased with increasing carbon number of the alkoxy group, but the mesophase transition temperature (Tt) and isotropic melting point (Ti) decreased. Degradation of the polymer started at 275 ° C-326 ° C and a 5% weight loss occurred at 350 ° C-392 ° C, indicating that it was relatively thermally stable.

3. P-HQ-n and P-BP-n (n = 8,12,16), P-DBP-12 and P-DDPSO-12 did not show any liquid crystal phase, and P- obtained by cooling in the molten state DBP-12 and P-DDPSO-12 were amorphous.

4. As a result of X-ray analysis, P-HQ-n and P-BP-n (n = 8,12,16) crystallized in layer structure, and the diameters of the polymer backbone were 5.20Å and 7.58Å, respectively.

Claims (6)

It consists of an aromatic diol derivative represented by the following formula (I) and the same equivalent of 2.5- dialkoxy terephthalate, having an intrinsic viscosity (ηinh) of 0.15-2.51 dl / g and decomposition at a temperature of 275 ° C-326 ° C. Wholly aromatic polyester, characterized in that the beginning.

Wherein R is C _n H _{2n + 1} (n = 8,12 or 16), and Ar is

to be. The method of claim 1 wherein the wholly aromatic polyester is characterized by a weight loss of 5% at 350 ℃-392 ℃. The method of claim 1 wherein the wholly aromatic polyester is characterized in that it is easily soluble in P-chlorophenol, THF, DMF, CHCl ₃ . Using pyridine as a solvent, the aromatic diol derivative represented by the above formula (I) and the same equivalent of 2,5-dialkoxy terephthalic acid chloride are mixed, and the mixture is heated at a temperature of 70 ° C-90 ° C for 3-5 hours. Method for producing a wholly aromatic polyester, characterized in that the reaction is produced. In tetrachloroethane, the aromatic diol derivative represented by the above formula (I) and the same equivalent of 2,5-dialkoxy terephthalic acid chloride are dissolved, pyridine is added thereto at room temperature under a nitrogen stream, and the mixture is then heated to 90 ° C-. Method for producing a wholly aromatic polyester, characterized in that the reaction is produced for 3-5 hours at a temperature of 100 ℃. At a temperature of 100 ° C., the aromatic diol derivative represented by the above formula (I) and the same equivalent of 2,5-dialkoxy terephthalic acid chloride are melted and reacted with dry nitrogen to remove the reaction byproduct HC1, followed by 250 ° C. Method of producing a wholly aromatic polyester, characterized in that the reaction for 4-6 hours by gradually heating until the temperature of -270 ℃.

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