GB2188277A

GB2188277A - Resin moulded product with immobilized polarization orientation

Info

Publication number: GB2188277A
Application number: GB08706534A
Authority: GB
Inventors: Tadahiro Asada; Kenji Hijikata; Takayuki Ishikawa
Original assignee: Polyplastics Co Ltd
Current assignee: Polyplastics Co Ltd
Priority date: 1986-03-26
Filing date: 1987-03-19
Publication date: 1987-09-30
Also published as: GB2188277B; GB8706534D0; JPS62246940A; SG2790G; JPH0653820B2

Abstract

A resin moulded product is made of a polyester exhibiting anisotropism in the molten state and/or a polyester containing partly in the same molecular chain a polyester exhibiting anisotropism in the molten state and is subjected to an electric field with heating and subsequently cooled, whereby polarisation orientation is immobilized. The product as a film, sheet, fibre or powder can be used at above 150 DEG C in a variety of applications eg display material, shutter element which requires heat resistance, or memory material.

Description

SPECIFICATION Resin molded product with immobilized polarization orientation The present invention relates to a resin molded product made of a polyesterwhich exhibits the anisotropism in the molten state and/or a polyester containing partly in the same molecular chain a polyester which exhi- bits the anisotropism in the molten state, said resin molded product being characterized in that it is subjected to an electric field with heating and subsequently cooled, whereby the polarization orientation isim- mobilized, and also to a process for producing the same.

It is known to persons skilled in the artthatwhen a compound having the intramolecular polarization undergoes poling with heating, or the application of a magnetic field and/or electric field with heating,the polarization is immobilized. The technique based on this knowledge is commonly used in the industry. Some ferroelectric polymeric compounds are known to be subject to the immobilization of polarization upon poling. Examples of such compounds include polyvinylidene fluoride, polytrifluoroethylene, and poly vinylidenecyanide-vinyl acetate copolymer. These ferroelectric polymers have some drawbacks.The control of orientation is not easy depending on the type of crystals, when it is necessary to bring about the polarization orientation, to immobilize the polarization in the amorphous region, orto bring about the orientation in a specific part alone. In addition, their polarization orientation can be used only at a lowtemperature range, i.e., 140 to 160 C, which is limited by their heat resistance. Moreover, their response is very slow to the application of electric field to bring about polarization orientation. (E.g., about 1 hour at 100 kV/cm) To shorten the response time, it is necessary to apply a high voltage and the resin is required to have a high dielectric breakdown strength to resist such a high voltage.

In view of the above-mentioned problems, the present inventors carried out extensive studies to develop a new material capable of polarization orientation which can be used at a high temperature and can undergo the poling within a short time. In their studies, the present inventors paid their attention to the responsetime and polarization orientation of a low-molecularweight liquid crystal compound, and they found thatthere are some polymeric compounds which have the properties of liquid crystal and also the properties of polarization orientation. This finding led to the present invention.

Accordingly, it is an object of the present invention to provide a resin molded product made of a polyester which exhibits the anisotropism in the molten state and/or a polyester containing partly in the same mole cular chain a polyester which exhibits the anisotropism in the molten state, said resin molded product being characterized in that it is subjected to an electricfield with heating and subsequently cooled, whereby the polarization orientation is immobilized.

It is a surprise to find that contrary to the expectation the resin molded product ofthis invention quickly responds to polarization orientation.

The polyester used in this invention is a polymer composition which exhibits the optical anisotropism in the molten state and is capable ofthermoplastic melt-processing. It generally falls underthe category of thermotropic liquid crystal polymer.

The polymer which forms the anisotropic molten phase has the properties of permitting the polymer molecularchainsto assume regular parallel arrangement in the molten state. The state in which molecules are arranged in such a manner is referred to as the liquid crystal state. The polymer like this is usually produced from a monomer which has a thin, long, and flat configuration, has a high rigidity along the long axis of the molecule, and has a plurality of chain extension linkages which are coaxial or parallel with one another.

The properties of the anisotropic molten phase can be determined by an ordinary polarization test using crossed nicols. More particularly, the properties can be determined with a Leitz polarizing microscope of 40 magnifications by observing a sample placed on a Leitz hot stage in a nitrogen atmosphere. The polymer is optically anisotropic. Namely, it transmits a light when it is placed between the crossed nicols. When the sample is optically anisotropic, the polarized light can be transmitted through it even in a still state.

The resin molded product of this invention is characterized in that the polyesterwhich exhibits the anissotropism in the molten state is one which contains an aromatic hydroxycarboxylic acid residue and arom atic substituted derivative residue thereof. The hydroxyl group and carboxylic acid group should preferably be substituted directly on the aromatic ring, and the hydroxyl group and carboxylic acid group may be on the same aromatic ring or different aromatic rings. In either cases, they should be in the same molecule ofthe aromatic cyclic compound. The aromatic hydroxycarboxylic acid resin should preferably be a compound composed of one or more kinds selected from hydroxybenzoic acid residue, hydroxynaphthoic acid residue, and their aromatic substituted derivative residue.The aromatic substituted derivative residue should have the substituent group selected from functional group which imparts the anisotropism to the intramolecular dipole moment of the hydroxycarboxylic acid compound and is at the substitution position to impart such anisotropism. In addition, the substituent group ofthe aromatic substituted derivative residue is one which imparts the anisotropism to the dipole moment in the direction of the line connecting the carbon atoms on the aromatic ring to which the hydroxyl group and carobxylic acid group are connected, and is atthesubstitu- tion position to impart such anisotropism. Preferred examples are those represented by the following form- ulas (I) to (VII).

(wherein the group consisting of X1, X2, and X3 and the group consisting of Y1, Y2, and Y3 are separated by a line which intersects at right angles a line connecting the carbon atoms on the aromatic ring to which the hydroxyl group and carboxylic acid group are connected, at the center thereof; each of said groups is one or more kinds selected from substituentgroupswhich differfrom one another in dipole moment; the same group does not contain those which differfrom one another in the direction of dipole moment; and the unsubstituted position in each group represents a hydrogen atom.) The substituent group is selected from cyano group, nitro group, aldehyde group, carboxylic acid ester, carboxylic acid group, hydroxyl group, hydrogen, halogen compound, amino group, imino group, azo group, alkoxy group, alkyl group, phenyl group, acyl group, sulfoxy group, and sulfide group. Preferably, it is selected from hydrogen, cyano group, nitro group, acetoxy group, chlorine, bromine, phenyl group, alkyl group, methoxy group, amino group, and alkyl-substituted amino group.

The above-mentioned polyesterwhich exhibits the anisotropism in the molten state may be a homo polymer or a block copolymer. In the latter case, the segments ofthe polyester are copolymerizedin the other polyesterwhich may not be capable of polarization orientation. The other polyester is one or more kinds selected from aromatic polyester, polycarbonate, polyethersulfone, polyacrylate, and polyalkyleneterephthalate.

The polymer which exhibits the anisotropism in the molten state may be contained in the otherthermo plastic polymer. It may be dispersed in the miscible form or immiscible form. Those which are uniformly dispersible are preferable, and their examples include aromatic polyester, polycarbonate, polyethersulfone, polyacrylate, and polyalkylene terephthalate.

The polyester which exhibits the anisotropism in the molten state may be produced by a variety of esterforming processes.

The monomer compounds can be reacted by melt acidolysis in the absence of any heat exchange fluid. In this process, the monomers are heated to form a melt of reactants. As the reaction proceeds, the solid polymer particles begin to suspend in the melt. In the final stage ofthe condensation reaction,the reaction system may be evacuated to facilitate the removal of volatile by-products such as acetic acid and water.

A slurry polymerization process may also be employed in the preparation of fully aromatic polyesters suitable for use in the present invention. In this process, the solid product is obtained in the form of suspension in a heat exchange medium.

In either of said melt acidolysis and slurry polymerization processes, the organic monomeric reactants from which the fully aromatic polyesters can be derived may be employed in the reaction in a modified form obtained by esterifying the hydroxyl group ofthe monomer at ambient temperature (i.e., in the form oftheir lower acyl esters). The lower acyl groups have preferably about 2to 4 carbon atoms. Preferably, acetate esters of the organic monomeric reactants are employed in the reaction. Also, the modified form (i.e., phenol ester) formed by esterifying the carboxylic acid group may be used for the reaction.

Typical examples of the catalysts that can be used in both of the melt acidolysis and slurry processes include dialkyltin oxides (such as dibutyltin oxide), diaryltin oxides, titanium dioxide, antimonytrioxide, alkoxytitanium silicates, titanium alkoxides, alkali metal and alkaline earth metal salts of carboxylic acids (such as zinc acetate), Lewis acids (such as BF3), and hydrogen halides and other gaseous acids (e.g., HC1).

The catalyst is generally used in an amount of about 0.001 to 1 wt%, particularly about 0.01 to 0.2 wt%, based on the monomer.

The aromatic polymers suitable for use in the present invention are substantially insoluble in ordinary solvents and, therefore, they are unsuitable for use in a solution processing. However, these polymers can be processed easily by the ordinary melt processing. Particularly preferred aromatic polymers are soluble in pentafluorophenol to some extent.

The aromatic polyesterwhich is preferably used in the present invention have a weight-average molecular weight of about 1,000 to 200,000, preferably about 2,000to 50,000, particularly about 3,000 to 25,000.

The molecular weight may be determined by gel permeation chromatography or other standard methods which need no polymer solution, such as a method in which terminal groups are determined by infrared spectroscipy using a compression-molded film sample. The molecular weight may also be determined by the light-scattering method using a solution of pentafluorophenol.

The above-mentioned aromatic polyester has an inherent viscosity (I.V.) of at least about 0.5 dl/g,for example, about 0.5 to 10.0 dl/g as measured in a 0.1 wt%solution in pentafluorophenol at60 C.

The polyester which exhibits the anisotropism in the moltent state may contain anotherferroelectric subst- ance. Such ferroelectric compound enhances the properties of the polyester used as a ferroelectric material.

The ferroelectric compound may be inorganic compounds, organic compounds, or polymeric compounds.

Examples of the inorganic compounds include quartz, lead zirconate titanate, potassium hydrogen phosphate, barium titanate, lead titanate, lead niobate, lithium niobate, lithium tantalate, strontium barium niobate, Pb(B1. 82)03, and PbTiO3.PbZrO2.Pb(B1. B2)03 (where B1 represents Mg, Co, Ni, Mn, and Zn; and B2 represents Nb, Ta, Sb, orW).

Examples ofthe organic compounds include low-molecular liquid crystal compounds, Rochelle salt, and triglycin sulfate. Explanation on low-molecular liquid crystal compounds will be found in "Ekisho noSaishin Gijutsu" (Latest Technology of Liquid Crystals) by Matsumoto and Tsunoda (Kogyo Chosakai) and "Handbook of Liquid Crystals" by K. Kelker and R. Hatz (Weinheim, 1980).

Examples of the polymeric compound include polymers and copolymers ofvinylidenefluoride,tri- fluoroethylene, vinylidene cyanide, and chloroacrylonitrile.

The polyester obtained in this invention is usually subjected to poling when it is formed into sheet orfilm. After poling, it may be used in the form of powder having polarization orientation. This powder may also be dispersed into athermosetting or thermoplastic resin.

Examples ofthe thermosetting resin include phenolic resin, epoxy resin, melamine resin, urea resin, un- saturated polyester resin, and alkyd resin.

Examples ofthe thermoplastic resin include polyethylene, polypropylene, polybutylene, polybutadiene, polyisoprene, polyvinyl acetate, polyvinyl chloride, polyvinylidenechioride, polystyrene, acrylic resin, ABS resin, AS resin, BS resin, polyurethane, silicone resin,fluoroplastic, cyan resin, polyacetal, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, aromatic polyester, polyamide, polyacrylonitrile, polyvinyl alcohol, polyvinyl ether, polyetherimide, polyamideimide, polyetherimide, polyetherketone, polyethersulfone, polysulfone, polyphenylene sulfide, and polyphenylene oxide.

Preferred ones are aromatic polyester, polycarbonate, polyethersulfone, polyacrylate, polyalkyleneter ephthalatetandpolymersandcopolymersderivedfromvinylidenefluoridestrifluoroethylenetvinylidene cyanide, and chloroacrylonitrile.

The application of electric field can be carried out by the method known to persons skilled in the art. Both sides ofthe sheet orfilm ofthe polyester of this invention are treated for electric conduction, and a voltage is applied to the sheet orfilm with heating. The voltage application may be performed continuously or inter- mittently (in pulse). The intermittent application in pulse is preferred for the ease of polarization orientation.

The object is achieved with minimum heating sufficientto impart kinetic energy that causes the polarization inversion. For complete polarization inversion, the heating temperature should be higher than the melting point of the polyester. At such a temperature the polarization orientation takes place very quickly because of the properties of liquid crystal the polyester originally possesses. Where the polarized anisotropic strain is required, heating below the melting point is preferred. After the treatment for polarization orientation,the molded product is cooled rapidly so that the orientation is immobilized.

The polyester and composite product thereof obtained in this invention may be incorporated with a variety of additives bythe method known to persons skilled in the art. The additives include plasticizer, antioxident, UV light absorber, antistatic agent, flame retardant, dye and pigment, surface treatmenttherefor, andre inforcing fiber and inorganicfiller.

The polyester and compound product thereof obtained in this invention may be formed into film, sheet, fiber, and powder for a variety of applications.

As mentioned above, the present invention provides a resin molded product made of a polyesterwhich exhibits the anisotropism in the molten state and/or a polyester containing partly in the same molecular chain a polyester which exhibits the anisotropism in the molten state, said resin molded product being characterized in that it is subjected to an electricfield with heating and subsequently cooled, wherebythe polarization orientation is immobilized. The resin molded product ofthis invention has several features. It has extremely high heat resistance. The molecules are extremely mobile in the molten state becausethe molecular chain is rigid and has the property of liquid crystal. It is quickly responsive to the application of electric field. Therefore, the resin molded product of this invention finds a large variety of application.It can be used in a hot environment above 1 500C in which the ordinary ferroelectric polymeric material cannot be used. It can be used as a display material or shutter element which requires heat resistance. It can also be used as a memory material and selective functional membrane if the part for the application of electricfield or the partforheating (by, for example, laser irradiation) are properly selected.

The above-mentioned method is also effective in eliminating the disadvantage inherent in the resin which exhibits the anisotropism in the molten state. For example, it physically controls the properties of excessive orientation, improves the strength of weld, and prevents the fibrillation which occurs in the case of excessive orientation.

Brief description of the drawings: Figure 1 is a chart showing the relation between the wave number and the absorbance which was obtained bymeasuring FTlRofthefilm used in this invention.

Figure2 is a microphotograph of the resin molded product of this invention observed under a polarization microscope.

Example 1 1261 parts by weight of 4-acetoxybenzoic acid and 691 parts by weight of 6-acetoxy-2-naphthoic acid were placed in a reactor provided with a stirrer, a nitrogen inlet tube, and a distillation tube. The mixturewas heated to 2500C under a nitrogen stream and stirred vigorously at that temperature for 3 h and then at 280'C for 2 h while acetic acid was distilled offfrom the reactor. The temperature was elevated to 320 C and the feeding of nitrogen was stopped. The pressure in the reactor was reduced graduallyto 0.1 mmHg after20 min. The mixture was stirred atthattemperature underthat pressure for 1 h.

The resulting polymer had an intrinsic viscosity of 5.4as determined in pentafluorophenol at a concentration of 0.1 wt% at 60 C.

The resulting polymer has the following constitutional units.

The resulting polymer was made into a 20- > m thick film by using aT-die extruder. The extruder and T-die were set at 3000C and 290 C, respectively. The film was uniaxially stretched at a draw ratio of 1/10. Thisfilm was examined with polarized light in the directions parallel to and perpendiculartothe orientation axis by using an FTIR made by Nippon Bunko Co., Ltd. The charts obtained in the examination are shown in Figures 1(a) and 1 (b). The chart obtained without using a polarizing plate is shown in Figure 1 (c). These charts show that the film in this example is highly oriented in the axial direction.

The uniaxially oriented film was held between two Nesa glass plates provided with lead wires. The assembly was inserted into a hot stage, and the film was observed under a polarization microscope provided with crossed nicols. Afibrous pattern characteristic of nematic liquid crystal was observed when thetem perature reached 80 C. Figure 2(a) shows the pattern observed through the crossed nicols at 310"C. When an AC voltage (100 V, 60Hz) was applied to the Nesa glass platethroughthe lead wires whilethe film was heated at 300"C, the visual field became dark within 12 seconds and the fibrous pattern of Figure 2(a) disappeared.

Figure 2(b) shows a pattern observed 20 seconds after the application of AC voltage (100 V). With the voltage applied, the temperature was lowered to 200 C. At 200 C, the application of voltage was suspended. Thefilm was allowed to cool to room temperature. After 1 week,thefilm was examined in the same manner as mentioned above. The visual field remained dark. This indicates that the polarization orientation took place in the direction in which the voltage was applied and the orientation was immobilized in the polymer.

The film sample was heated again to 3000C and the Nesa glass plates were slided in the opposite direction so that shear is exerted to thefilm sample. The film samplewas observed under a polarization microscope in the same manner as mentioned above. The same fibrous pattern as that observed before the voltage application was observed.

Table 1 shows the results obtained under different conditions.

Table 1 Voltage (V) of Type of electric Time for dark Optical density electric field field change (sec) log lo/l 40 60 Hz, AC 870 1.7 60 60 Hz, AC 240 2.2 80 60 Hz, AC 100 2.3 100 60 Hz, AC 12 2.4 100 DC 10 2.4 Comparative Example 1 The same film sample as obtained in Example 1 was heated to 400 Cwithout applying the voltage and observed under a polarization microscope. The visual field did not become dark. Then, the temperature of the film sample W3 lowered eo20QQC; but the fibrous pattern did not disappear.

Comparative Example 2 166 parts by weight ofterephthalic acid, 166 parts by weight of isophthalic acid, and 250 parts by weight of diacetoxymethylhydroquinonewereplaced in a reactor provided with a stirrer, a nitrogen inlet tube, and a distillation tube. The mixture was heated to 260 C under a nitrogen stream and stirred vigorously atthat temperature for 2.5 h and then at 2800C for 3 h while acetic acid was distilled offfrom the reactor. The temperature was elevated to 3200C and the feeding of nitrogen was stopped. The pressure in the reactorwas reduced gradually to 0.1 mmHg after 15 min. The mixture was stirred atthattemperature under that pressure for1 h.

The resulting polymer had an intrinsic viscosity of 0.87 as determined in a 1:1 mixed solventoftetra- chloroethane and phenol at a concentration of 0.5 wt%.

The resulting polymerwas made into a film sample in the same manner as in Example 1 (extruderat270"C and T-die at 260"C). The film sample was observed under a polarization microscope as in Example 1.Thefilm sample exhibited a fibrous pattern at 250"C. A DC voltage (100 V and pulse)was applied for 30 minutes at 300 C. The visual field did not become dark, and the fibrous pattern did not disappear. The same was true of thefilmsampleaftercooling.

Example2 138.2 parts by weight of polyethylene terephthalate (having an intrinsic viscosity of 0.36) was added to 162 parts by weight of polyester (having an intrinsic viscosity of 0.77) preliminarily polymerized at 260"Cfor3 hours in the same manner as in Example 1. The reaction was continued in the same reactor at 2800for4 hours with vigorous agitation. The reaction temperature was raised to 3200C and the feeding of nitrogen was stopped. The reactor was evacuated to 0.1 mmHg after 15 minutes. Stirring was continued for 1 hour atthis temperature and pressure.

The resulting polymer had an intrinsicviscosity of 2.9 as determined in pentafluorophenol at a concentration of 0.1 wt% at 60 C.

The resulting polymer was found to be composed of 40 mol% of polyethylene terephthalate and 60 mol% of hydroxybenozic acid and hydroxynaphthoic acid.

The polymer was made into a film in the same manner as in Example 1, and the film was observed on the hotstage. Thefibrous pattern appeared at 230"C, and thevisual field became darkwhen an ACvoltage (100V) was applied for 20 seconds at 280 C. The darkvisual field remained after the film was allowed to cool at room temperature. The fibrous pattern was restored when the film was subjected to shear with heating. The results are shown in Table 2.

Table 2 Voltage (V) of Type of electric Time for dark Optical density electricfield field change (sec) Log lo/l 60 60 Hz, AC 1100 2.1 80 60 Hz, AC 215 2.2 100 60 Hz, AC 20 2.3 100 DC 18 2.3 Example 3 900 parts by weight of 4-acetoxybenzoic acid, 431 parts by weight of 4-acetoxy-3-chlorobenzoic acid, and 690 parts by weight of 6-acetoxy-2-naphthoic acid were placed in a reactor provided with a stirrer, a nitrogen inlet tube, and a distillation tube. The mixture was heated to 250"C under a nitrogen stream and stirred vigorously atthattemperature for 3 hand then at280 Cfor2 h while acetic acid was distilled off from the reactor. The temperature was elevated to 3200C and the feeding of nitrogen was stopped.The pressure in the reactor was reduced gradually to 0.1 mmHg after 20 min. The mixture was stirred atthattemperature under thatpressureforl h.

The resulting polymer had an intrinsic viscosity of 5.0 as determined in pentafluorophenol at a concentration of 0.1 wt%at60 C.

The polymerwas made into a film inthesame manner as in Example 1, and theflim was observed onthe hot stage. The firbrous pattern appeared at 250"C, and the visual field became dark when a DC voltage (1 00V, pulse) was applied for 19 seconds at 280#C. The darkvisual field remained after the film was allowed to cool at room temperature. The fibrous pattern was restored when the film was subjected to shear with heating. The results are shown in Table 3.

Table 3 Voltage (V) of Type of electric Time for dark Optical density electricfield field change (sec) log lo/l 60 60Hz,AC 210 2.2 80 60 Hz, AC 95 2.3 100 60 Hz, AC 11 2.4 100 DC 9 2.4 Example 4 38.4 parts byweightof p-amylbenzoic acid and 36.0 parts by weight of acetoxybenzoic acid were reacted under reflux in 200 ml oftoluene. Then, 41.2 parts by weight of p-amylphenol was added, and the reaction was continued under reflux. Thus there was obtained amylphenolbenzoate ester (amylphenyl carboxylate).

This low-molecular compound had a Tm of 780C. It exhibited the Schlieren pattern or the properties of nem- atic liquid crystal under a polarization microscope. Twenty parts by weight of the low-molecularcompound (A) was added to 100 parts by weight ofthe polymer obtained in Example 1, and the resulting composition was formed into a film in the same manner as in Example 1. The film was optically observed. Thefibrous pattern was observed at 250"C, and the visual field became dark when a DC voltage (100 V, pulse) was applied for 7 seconds at 280 C. The dark visual field remained after the film was allowed to cool at room temperature.

The fibrous pattern was restored when the film was subjected to shear with heating.

Example 5 60 parts of the polymer obtained in Example 2 (which exhibits the anisotropism in the molten state) was mixed with 40 parts by weight of polyethylene terephthalate. The mixture was made into afilm andthefilm was observed in the same same manner as in Example 1. Thevisual field became dark when a DCvoltage (100 V, pulse) was applied for 20 seconds at 280 C. The log Idl was 1.8.

Claims

1. A resin molded product made of a polyester which exhibits the anisotropism in the molten state and/or a polyester containing partly in the same molecular chain a polyesterwhich exhibits the anisotropism in the molten state, said resin molded product being characterized in that it is subjected to an electric field with heating and subsequently cooled, whereby the polarization orientation is immobilized.

2. A resin molded product as set forth in Claim 1 ,wherein the polyesterwhich exhibits the anisotropism in the molten state is one which is composed mainly of an aromatic hydroxycarboxylicacid residue and one or more kinds of aromatic substituted derivative residuesthereof.

3. A resin molded product as set forth in Claim 2, wherein the aromatic hydroxycarboxylic acid residue is a hydroxybenzoic acid residue or hydroxynaphthoic acid residue.

4. A resin molded product as setforth in Claim 1,wherein the polyester containing partly in the same molecular chain a polyester which exhibits the anisotropism in the molten state is a copolymer composed of a polyester which exhibits the anisotropism in the molten state and one or more kinds selected from other aromatic polyesters, polycarbonate, polyether sulfone, polyacrylate, and polyalkylene terephthalate.

5. A resin molded product as set forth in Ciaim 1, wherein the polyester which exhibits the anisotropism in the molten state and/or the polyester containing partly in tie same molecular chain a polyesterwhich exhibits the anisotropism in the molten state is contained in other thermoplastic polymer.

6. A resin molded product as set forth in Claim 2, wherein the substituent group of the aromatic substitu ted derivative residue is one which imparts the anisotropism to the intramoleculardipole moment of the hydroxycarboxylic acid compound and is at the substiwtion position to impart such anisotropism.

7. A resin molded product as set for#h in Claim 2, wherein the substituent group of the aromatic substitu- ted derivative residue is one which imparts the anisotropism to the dipole moment in the direction of the line connecting the carbon atoms on the aromatic ring to which the hydroxyl group and carboxylic acid group are connected, and is at the substitution position to impart such anisotropism.

8. A resin molded product as set forth in Claim 2, wherein the aromatic hydroxycarboxylic acid residue is composed of one or more kinds selected from the following formulas (I) to (VII). (wherein the group consisting ofX1,X2, and X3 and the group consisting oft1, Y2, and Y3 are separated by a line which intersects at right angles a line connecting the carbon atoms on the aromatic ring to which the hydroxyl group and carboxylic acid group are connected, at the center thereof; each of said groups is one or more kinds selected from substituent groups which differfrom one another in dipole moment; the same group does not contain those which differfrom one another in the direction of dipole moment; and the unsubstituted position in each group represents a hydrogen atom.)

9. A resin molded product as setforth in any of Claims 6to 8, wherein the substituentgroup is one or more kinds selected from cyano group, nitro group, aldehyde group, carboxylic acid ester, carboxylic acid group hydrnx','l group, hydrogen, halogen compound, amino group, imino group, azo group, alkoxy group, aikylgroup,pilsn,/lgroup,acylgnoi~p,sul,oxygl-ouptai7dSuiridegi-oup.

10. A resin molded product as set forth in any of Claims Sto 8,whereinthe substituent group is one or more kinds selected from hydrogen, cyano group, nitro group, acetoxy group, chlorine, bromine, phenyl group, alkyl group, methoxy group, amino group, and alkyl-substituted amino group.

11. A resin molded product as set forth in Claim 1, wherein the polyesterwhich exhibits the anisotropism in the moltentstate is one which has a molecular weight of 2,000 to 50,000.

12. A resin molded product as set forth in Claim 1,wherein the polyester which is subjected to an electric field is one which contains a ferroelectriccompound.