Aromatic polysulfone resin and method for producing same

Abstract

An aromatic polysulfone resin having a yellowness index of 50 or higher and a weight average molecular weight of 25,000 to 45,000 is provided.

Claims

1. An aromatic polysulfone resin having a repeating unit represented by formula (1):
-Ph.sup.1-SO.sub.2-Ph.sup.2O(1) wherein Ph.sup.1 and Ph.sup.2 each independently represent a phenylene group, and each hydrogen atom in the phenylene group may be independently substituted with an alkyl group of 1 to 5 carbon atoms, an aryl group of 6 to 15 carbon atoms or a halogen atom; a yellowness index of 50 or higher; and a weight average molecular weight of 25,000 to 45,000, and wherein the proportion of the repeating unit represented by formula (1) relative to the total weight of all structural units that constitute the aromatic polysulfone resin is 80 to 100% by weight.

2. The aromatic polysulfone according to claim 1, having a light transmittance at 380 nm of not more than 5% and a light transmittance at 650 nm of at least 60%.

3. The aromatic polysulfone according to claim 1, wherein the proportion of the repeating unit represented by formula (1) relative to the total weight of all the structural units that constitute the aromatic polysulfone resin is 100% by weight.

4. A method for producing an aromatic polysulfone resin having a yellowness index of 50 or higher and a weight average molecular weight of 25,000 to 45,000, the method comprising a step of melt kneading an aromatic polysulfone resin having a weight average molecular weight of 50,000 to 70,000 at a temperature of 390 C. or higher.

Description

EXAMPLES

(1) Examples of the present invention are presented below, but the present invention is in no way limited by these examples.

(2) [Measurement of Mw of Aromatic Polysulfone Resins]

(3) Gel permeation chromatography (GPC) analyses were performed under the following conditions to determine Mw.

(4) Sample: 50 L injection of an N,N-dimethylformamide solution of the aromatic polysulfone resin with a concentration of 0.003 g/mL

(5) Columns: two connected TSKgel GMH.sub.HR-H (7.8 mm300 mm) columns, manufactured by Tosoh Corporation

(6) Column temperature: 40 C.

(7) Eluent: N,N-dimethylformamide

(8) Eluent flow rate: 0.8 mL/minute

(9) Detector: differential refractive index meter (RI)+multi angle light scattering photometer (MALS)

(10) Standard reagents: polystyrene

(11) [Evaluation of Yellowness Index of Aromatic Polysulfone Resins]

(12) The aromatic polysulfone resins obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were each molded into a flat plate-like test piece with a size of 64 mm64 mm (thickness: 3 mm), using a PS40E1ASE injection molding machine manufactured by Nissei Plastic Industrial Co., Ltd. under conditions including a cylinder temperature of 370 C. a mold temperature of 150 C. and an injection speed of 40%. A colorimeter ZE-2000 manufactured by Nippon Denshoku Industries Co., Ltd. was then used to measure the yellowness index of each of these flat plate-like test pieces based on JIS K 7373.

(13) [Evaluation of Light Transmittance of Aromatic Polysulfone Resins]

(14) The aromatic polysulfone resins obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were each molded into a flat plate-like test piece with a size of 64 mm64 mm (thickness: 3 mm), using a PS40E1 ASE injection molding machine manufactured by Nissei Plastic Industrial Co., Ltd. under conditions including a cylinder temperature of 370 C., a mold temperature of 150 C. and an injection speed of 40%. A spectrophotometer U-3500 manufactured by Hitachi, Ltd. was then used to measure the light transmittance of each of these flat plate-like test pieces at 380 nm and 650 nm.

Example 1

(15) A polymerization tank fitted with a stirrer, a nitrogen inlet tube, a thermometer, and a condenser having a receiver at the tip thereof was charged with 500 g of 4,4-dihydroxydiphenylsulfone, 589 g of 4,4-dichlorodiphenylsulfone, and 942 g of diphenyl sulfone as a polymerization solvent, and the temperature was raised to 180 C. while the inside of the tank was flushed with nitrogen gas. Next, 283 g of potassium carbonate was added to the obtained solution, the temperature was then raised gradually to 290 C., and the reaction was allowed to proceed at 290 C. for a further 2 hours. The thus obtained reaction solution was cooled to room temperature (about 25 C.) and solidified, and following fine crushing, the product was washed several times with hot water and washed several times with a mixed solvent of acetone and methanol, and subsequently dried by heating at 150 C. thus obtaining a powder of an aromatic polysulfone resin with terminal chloro groups.

(16) The Mw of this aromatic polysulfone resin (the Mw prior to melt kneading) was then measured.

(17) Subsequently, the obtained aromatic polysulfone resin was supplied to the cylinder of a twin-screw extruder (PCM-30, manufactured by lkegai, Ltd.), strands were obtained by performing melt kneading and extrusion at a cylinder temperature of 390 C., and these strands were cut to obtain pellets.

(18) Next, the Mw of the thus obtained aromatic polysulfone resin (the Mw following melt kneading) was measured.

(19) Subsequently, the yellowness index and the light transmittance of the obtained aromatic polysulfone resin were measured.

Example 2

(20) A polymerization tank fitted with a stirrer, a nitrogen inlet tube, a thermometer, and a condenser having a receiver at the tip thereof was charged with 500 g of 4,4-dihydroxydiphenylsulfone, 589 g of 4,4-dichlorodiphenylsulfone, and 942 g of diphenyl sulfone as a polymerization solvent, and the temperature was raised to 180 C. while the inside of the tank was flushed with nitrogen gas. Next, 287 g of potassium carbonate was added to the obtained solution, the temperature was then raised gradually to 290 C. and the reaction was allowed to proceed at 290 C. for a further 2 hours. The thus obtained reaction solution was cooled to room temperature (about 25 C.) and solidified, and following fine crushing, the product was washed several times with hot water and washed several times with a mixed solvent of acetone and methanol, and subsequently dried by heating at 150 C., thus obtaining a powder of an aromatic polysulfone resin with terminal chloro groups. The Mw of this aromatic polysulfone resin (the Mw prior to melt kneading) was then measured.

(21) Subsequently, the obtained aromatic polysulfone resin was supplied to the cylinder of a twin-screw extruder (PCM-30, manufactured by Ikegai, Ltd.), strands were obtained by performing melt kneading and extrusion at a cylinder temperature of 395 C., and these strands were cut to obtain pellets.

(22) Next, the Mw of the thus obtained aromatic polysulfone resin (the Mw following melt kneading) was measured.

(23) Subsequently, the yellowness index and the light transmittance of the obtained aromatic polysulfone resin were measured.

Example 3

(24) An aromatic polysulfone resin obtained using the same method as Example 2 was supplied to the cylinder of a twin-screw extruder (PCM-30, manufactured by lkegai, Ltd.), strands were obtained by performing melt kneading and extrusion at a cylinder temperature of 400 C., and these strands were cut to obtain pellets.

(25) Next, the Mw of the thus obtained aromatic polysulfone resin (the Mw following melt kneading) was measured.

(26) Subsequently, the yellowness index and the light transmittance of the obtained aromatic polysulfone resin were measured.

Comparative Example 1

(27) A polymerization tank fitted with a stirrer, a nitrogen inlet tube, a thermometer, and a condenser having a receiver at the tip thereof was charged with 500 g of 4,4-dihydroxydiphenylsulfone, 593 g of 4,4-dichlorodiphenylsulfone, and 949 g of diphenyl sulfone as a polymerization solvent, and the temperature was raised to 180 C. while the inside of the tank was flushed with nitrogen gas. Next, 287 g of anhydrous potassium carbonate was added to the obtained solution, the temperature was then raised gradually to 290 C., and the reaction was allowed to proceed at 290 C. for a further 2 hours. The thus obtained reaction solution was cooled to room temperature (about 25 C.) and solidified, and following fine crushing, the product was washed several times with hot water and washed several times with a mixed solvent of acetone and methanol, and subsequently dried by heating at 150 C., thus obtaining a powder of an aromatic polysulfone resin with terminal chloro groups. Next, the Mw of this aromatic polysulfone resin (the Mw prior to melt kneading) was measured.

(28) Subsequently, the obtained aromatic polysulfone resin was supplied to the cylinder of a twin-screw extruder (PCM-30, manufactured by lkegai, Ltd.), strands were obtained by performing melt kneading and extrusion at a cylinder temperature of 380 C., and these strands were cut to obtain pellets.

(29) Next, the Mw of the thus obtained aromatic polysulfone resin (the Mw following melt kneading) was measured.

(30) Subsequently, the yellowness index and the light transmittance of the obtained aromatic polysulfone resin were measured.

Comparative Example 2

(31) A polymerization tank fitted with a stirrer, a nitrogen inlet tube, a thermometer, and a condenser having a receiver at the tip thereof was charged with 500 g of 4,4-dihydroxydiphenylsulfone, 593 g of 4,4-dichlorodiphenylsulfone, and 949 g of diphenyl sulfone as a polymerization solvent, and the temperature was raised to 180 C. while the inside of the tank was flushed with nitrogen gas. Next, 287 g of anhydrous potassium carbonate was added to the obtained solution, the temperature was then raised gradually to 290 C. and the reaction was allowed to proceed at 290 C. for a further 2.5 hours. The thus obtained reaction solution was cooled to room temperature (about 25 C.) and solidified, and following fine crushing, the product was washed several times with hot water and washed several times with a mixed solvent of acetone and methanol, and subsequently dried by heating at 150 C., thus obtaining a powder of an aromatic polysulfone resin with terminal chloro groups. The Mw of this aromatic polysulfone resin (the Mw prior to melt kneading) was then measured. The obtained aromatic polysulfone resin was supplied to the cylinder of a twin-screw extruder (PCM-30, manufactured by Ikegai, Ltd.), strands were obtained by performing melt kneading and extrusion at a cylinder temperature of 385 C., and these strands were cut to obtain pellets.

(32) Next, the Mw of the thus obtained aromatic polysulfone resin (the Mw following melt kneading) was measured.

(33) Subsequently, the yellowness index and the light transmittance of the obtained aromatic polysulfone resin were measured.

Comparative Example 3

(34) The aromatic polysulfone resin obtained in Example 1 was supplied to the cylinder of a twin-screw extruder (PCM-30, manufactured by lkegai, Ltd.), strands were obtained by performing melt kneading and extrusion at a cylinder temperature of 365 C., and these strands were cut to obtain pellets.

(35) Next, the Mw of the thus obtained aromatic polysulfone resin (the Mw following melt kneading) was measured using the method for measuring the Mw of aromatic polysulfone resins described above

(36) Further, the yellowness index and the light transmittance of the obtained aromatic polysulfone resin were also measured using the measurement methods described above. The measurement results for the weight average molecular weights (Mw) of the aromatic polysulfone resin before and after melt kneading, the yellowness index and the light transmittance are shown in Table 1.

(37) TABLE-US-00001 TABLE 1 Example Example Example Comparative Comparative Comparative 1 2 3 Example 1 Example 2 Example 3 Weight average prior to melt 51000 65000 65000 42000 45000 51000 molecular weight kneading Mw following melt 36000 41000 33000 36000 32000 51000 kneading Yellowness 57 64 72 25 41 24 index Transmittance % 2.5 1.7 1.3 33 9.0 33 (380 nm) Transmittance % 63 63 62 81 62 81 (650 nm)

INDUSTRIAL APPLICABILITY

(38) Because the aromatic polysulfone resin of the present invention does not contain an ultraviolet absorber, when a molded article molded from the resin is used over an extended period of time, it is expected that any deterioration in the ultraviolet cutting effect can be suppressed, meaning the resin is useful industrially.