JPH0452286B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel high-rigidity polyesterimide that can be melt-molded and has excellent mechanical properties. In recent years, there has been an increasing demand for materials with excellent rigidity, heat resistance, and chemical resistance, whether fibers, films, or molded products. Polyester has come to be widely accepted for use in general molded products, but many polyesters have poor mechanical properties such as flexural modulus, so they are not suitable for applications that require high strength. In order to improve this mechanical property, it is known to blend reinforcing materials such as calcium carbonate and glass fiber, but this increases the specific gravity of the material, which reduces the lightweight advantage of plastic. During molding, the molding machine is subject to severe wear and tear, and there are many practical problems. In recent years, polyester has been used as a material that does not require reinforcement and is suitable for applications that require high strength.
Liquid crystalline polyester has started to attract attention.
Particularly noteworthy was the Journal of Polymer Science Polymer Chemistry Edition, Volume 14 (1976) 2043.
This was after W.J. Jackson announced a thermal liquid crystalline polymer consisting of polyethylene terephthalate and hydroxybenzoic acid on page 1. Among them, Jackson
They reported that this liquid crystal polymer exhibits more than 5 times the stiffness, 4 times the strength, and 25 times the impact strength of polyethylene terephthalate, demonstrating new possibilities for high-performance resins. Since then, JP-A-53-
65421 (DuPont), JP 54-50594 (Celanese), JP 55-21491 (ICI), JP 55-50022
(Rhône-Poulenc), JP-A-55-106220 (Fiber Industry), etc., and improved strength and rigidity,
The development of liquid crystalline polyester continues with the aim of achieving both melt moldability. However, although over 100 types of liquid crystalline polyesters have already been proposed, none have yet been successfully molded into molded products.
This is because these polymers exhibit a high degree of orientation in the molten state, resulting in large anisotropy in mechanical properties. The inventors of the present invention have conducted intensive studies to alleviate the anisotropy of mechanical properties without sacrificing high rigidity.
We have arrived at the present invention. The gist of the present invention is a structural unit represented by the following formulas A and B, Consisting essentially of unit A and 33 to 57 mol% unit B
A highly rigid polyesterimide containing 67 to 43 mol% of The highly rigid polyesterimide of the present invention exhibits liquid crystallinity in a molten state, can be melt-molded, and has the characteristics of having little anisotropy in the physical properties of a molded product. The present invention will be described in detail below. The highly rigid polyesterimide of the present invention essentially consists of the two structural units A and B described above. Unit A is introduced from poly(ethylene terephthalate) or bis(β-hydroxyethyl) terephthalate.
Unit A is the high rigidity polyesterimide to be produced.
33-57 mol% is suitable. If it is too large, the rigidity will not be high, and if it is too small, the amount of unit B will inevitably increase and the polymerizability will decrease. Unit B is derived from a dicarboxylic acid component such as terephthalic acid or a derivative thereof, such as an alkyl ester, and a bisphenol or a derivative thereof, such as a dialkyl ester, containing an imide group derived from p-aminophenol and hydroxyphthalic acid as the diol component. be done.
The preferred amount of unit B is 67 to 43 mol%. The polyesterimide of the present invention is characterized by having units B. As mentioned above, there are many proposals for liquid crystal polyesters, but all of them have large anisotropy in mechanical properties. However, the polyesterimide of the present invention uses liquid crystalline polyester to alleviate the anisotropy of mechanical properties without sacrificing high rigidity. That is, in this unit B, the hydroxyl group that contributes to bonding is located asymmetrically with respect to the main chain of the resulting polymer, and has the effect of relaxing the symmetry in the molecular structure developed from the unit A. Furthermore, since unit B contains an imide bond in its molecule, it can be expected to have intermolecular interactions that are superior to ester bonds, although not as strong as amide bonds, and can disperse forces in the direction perpendicular to the molecular chain. can. By including the unit B having these properties, the present invention can provide a living product with small anisotropy of physical properties, unlike many liquid crystal polyesters proposed so far. The highly rigid polyesterimide of the present invention has a logarithmic viscosity of at least 0.4 dl/g (logarithmic viscosity is the natural logarithm of the relative viscosity divided by the concentration of the sample solution, and in this measurement, the viscosity solvent was tetrachloroethane. /phenol=1/1 (weight ratio) (measured at a concentration of 0.5 wt%), and has a logarithmic viscosity of, for example, 0.5 to 1.5 dl/g. An optical method using a polarizing microscope is suitable for determining whether or not a material can exhibit anisotropy in a molten state. That is, optical anisotropy is observed by transmission or reflection under a polarizing microscope equipped with a heat stage. When the temperature is gradually increased from room temperature, polymers that do not exhibit anisotropy are observed to immediately change to an isotropic melt at the melting point, but polymers that exhibit anisotropy generally change from a crystalline state to a certain state. It becomes a liquid crystal state at a certain temperature, and exhibits a stable liquid crystal state over a fairly wide temperature range (temperature range of 10°C or more, for example). Thereafter, the temperature increases and the melt changes to an isotropic melt. The simplest method is to determine anisotropy by observing such optical anisotropy. The highly rigid polyesterimide according to the present invention can be easily produced by a combination of melt polymerization and solid phase polymerization as shown in Examples. In addition, it can be melted and molded at a resin temperature of about 350°C, and the molded product has high rigidity, making it useful as a material for small precision parts that require thin wall construction (e.g., electronic material parts such as connectors, sockets, and bobbins). . EXAMPLES The present invention will be specifically explained below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. Reference example (a) Synthesis of 4-hydroxyphthalic acid 9.1g (0.05 mol) and p
- 5.45 g (0.05 mol) of aminophenol are dissolved in 100 ml of N-methylpyrrolidone. After refluxing for 4 hours, cool. Pour the reaction product into 500ml of water and white-green crystals precipitated. It was washed with water and dried. Element molecule, calculated value (actual value); C65.88 (65.58)
H3.55 (3.52) N5.49 (5.54). (B) The synthesis of phenol was followed by the most common method of acetylation. That is, () was dissolved in pyridine, excess acetic anhydride was added and refluxed for 4 hours, and the reaction solution was poured into water to precipitate pale yellow crystals. After that, it was washed with water and dried. Elemental analysis, calculated value (actual value); C63.72
(63.78) H5.86 (3.87) N4.13 (412). Example 1 and Comparative Examples 1 to 3 Polyethylene terephthalate (Mitsubishi Chemical Industries, Ltd.)
0.30 mol (57.6 g), terephthalic acid
0.35 mol (58.1 g) and 0.35 mol (118.6 g) of the compound were charged into a polymerization tube equipped with double helical wings, and after purging with nitrogen, the mixture was heated at 275° C. to melt. When stirring was continued for 3 hours at normal pressure, the polymer solidified into lumps and some powder. The pressure in the polymerization tube
After adjusting the pressure to 0.4 mmHg and continuing stirring for an additional hour, the partially powdery mass was taken out. crush the polymer
Solid phase polymerization was carried out at 300°C and 0.5 mmHg for 9 hours.
Although the polymer was obtained in almost 100% yield, it was not possible to measure the viscosity because some of it was insoluble. The results of elemental analysis of the obtained polymer are as follows. C H N * Calculated value (%) 66.74 3.27 2.55 Actual value (%) 66.85 3.21 2.62 * Value as charging ratio = composition ratio Figure 1 shows the infrared absorption spectrum chart of the obtained polymer. From these results, it can be seen that polyester is produced at a composition ratio that corresponds to the charging ratio of each raw material component. This polymer has a temperature range from 250°C to 350°C.
It exhibited optical anisotropy in the molten state in the temperature range up to ℃. Optical anisotropy was observed using a Nikon polarizing microscope POH model equipped with a Zeiss heat stage. This polymer was made into a strand shape using an extruder at 350°C, and then manufactured using Sonic Modulus (ASTMF89-
68) was measured and shown in Table 1 along with the Sonic modulus values of other polymers. The Sonic Modulus value is measured using the Dynamic Modulus Tester from Toyo Seiki Seisakusho Co., Ltd.
Using PPM-5R, measure the speed of sound (υ) that travels through the strand-shaped polymer, and calculate from Laplace's equation E=ρυ ² E: Sonic modulus ρ: Density (using density gradient tube) υ: Sound speed did.

[Table] Examples 2 to 3 and Comparative Examples 4 to 5 The polymer obtained in Example 1 was extruded to a size of 5 mm.
Make it into a φ strand, 3mm from this strand.
A corner chip was cut out and its compressive strength was measured. The compressive strength was 1 mm/sec, and the maximum load required to deform 10% of the initial thickness was divided by the cross-sectional area (ASTMD-1621). The number of test pieces is 5 in each direction parallel to and perpendicular to the strand. The measuring device is Tensilon testing machine (Toyo Baldwin)
was used. Table 3 shows representative liquid crystalline polyesters (manufactured by Mitsubishi Chemical Industries, Ltd., intrinsic viscosity
0.66 (tetrachlorethylene/phenol 50/
50 (weight ratio) of polyethylene terephthalate (measured at 30 °C at a concentration of 1 g/dl in a mixed solvent) and p
- Compressive strength of (produced from 60 mol% acetoxybenzoic acid) was measured and is also shown.

[Table] Further, the polymer obtained in Example 1 was molded into a flat plate of 80 x 80 x 3 (mm) using an injection molding machine (model AU-30, manufactured by Nissei Plastics Co., Ltd.) using a film gate. The cylinder temperature was 350-385°C. The same polymer used in Comparative Example 4 was also molded in the same manner. The cylinder temperature was set at 230-250°C. The flat plate was cut into strips in the resin flow direction (MD) and the direction perpendicular to it (TD), and the flexural modulus and flexural strength were measured (ASTMD790). The measuring device used was a Tensilon testing machine (Toyo Baldwin). Table 4 shows the results.
Shown below.

【table】 [Brief explanation of the drawing]

Figure 1 is an infrared absorption spectrum of the polyesterimide obtained in Example 1.

Claims (1)

[Scope of Claims] 1 Structural units represented by the following formulas A and B, Consisting essentially of unit A and 33 to 57 mol% unit B
A highly rigid polyesterimide containing 67 to 43 mol% of