FOAM MOLDED BODY

Abstract

An object of the present invention is to provide a molded body that is easy to produce and obtained by foaming a polycarbonate copolymer containing, as a raw material, isosorbide that is lightweight and excellent in mechanical properties and like. The present invention relates to a foam-molded body containing a polycarbonate copolymer having a structural unit derived from a dihydroxy compound represented by the following formula (1):

##STR00001##

and a structural unit derived from other dihydroxy compounds, and having a glass transition temperature (Tg) of less than 145 C.

Claims

1: A process for preparing a foam-molded body of a resin composition, the process comprising: foam-molding said resin composition by injection foaming, wherein the injection foaming involves expansion of a cavity with a foaming agent, said resin composition comprising a polycarbonate copolymer comprising: a structural unit derived from a dihydroxy compound (A) represented by formula (1): ##STR00006## and a structural unit derived from other dihydroxy compound (B), wherein the polycarbonate copolymer has a glass transition temperature (Tg) of less than 145 C., and wherein the foaming agent is at least one selected from the group consisting of a volatile foaming agent, an inorganic foaming agent, and a decomposition-type foaming agent.

2: The process of claim 1, wherein the dihydroxy compound is at least one structural unit selected from the group consisting of: a structural unit derived from a dihydroxy compound represented by formula (2):
HOR.sup.1OH(2), wherein R.sup.1 represents a substituted or unsubstituted cycloalkylene group having a carbon number of 4 to 20; a structural unit derived from a dihydroxy compound represented by formula (3):
HOCH.sub.2R.sup.2CH.sub.2OH(3), wherein R.sup.2 represents a substituted or unsubstituted cycloalkylene group having a carbon number of 4 to 20; a structural unit derived from a dihydroxy compound represented by formula (4):
H(OR.sup.3).sub.pOH(4), wherein R.sup.3 represents a substituted or unsubstituted alkylene group having a carbon number of 2 to 10, and p is an integer of 2 to 50; and a structural unit derived from a dihydroxy compound represented by the following formula (5):
HOR.sup.4OH(5) wherein R.sup.4 represents a substituted or unsubstituted alkylene group having a carbon number of 2 to 20 or a group containing a substituted or unsubstituted acetal ring.

3-5. (canceled)

6: The process of claim 1, wherein the foam-molded body has an expansion ratio, [(density before foaming)/(density after foaming)], of 1.1 to 100 times.

7. (canceled)

8: The process of claim 1, wherein the foaming agent is an inorganic gas.

9: The process of claim 8, wherein the inorganic gas is a nitrogen gas or a carbon dioxide gas.

10. (canceled)

11: The process of claim 1, wherein the foaming agent is present in an amount from 0.1 parts by mass or more to 20 parts by mass or less per 100 parts by mass of the polycarbonate copolymer.

12: The process of claim 1, wherein the foam-molded body has an expansion ratio, [(density before foaming)/(density after foaming)], of 3.47 to 100.

13: The process of claim 1, wherein the foam-molding is performed at a temperature that is from 5-200 C. higher than the glass transition temperature (Tg) of the polycarbonate copolymer.

14: The process of claim 1, wherein the expansion of the cavity is started within 0.1 seconds before or after a completion of filling of the mold with the resin.

Description

EXAMPLES

[0157] The present invention is described in greater detail below by referring to Examples, but the present invention is not limited to these Examples as long as the gist thereof is observed. Incidentally, the values of various production conditions and evaluation results in the following Examples have a meaning as a preferred value of the upper limit or lower limit in the embodiment of the present invention, and the preferred range may be a range defined by a combination of the upper or lower limit value above and the value in Example below or a combination of values in Examples.

<Glass Transition Temperature (Tg)>

[0158] About 10 mg of the sample was heated at a temperature rise rate of 10 C./min and measured by using a differential scanning calorimeter (DSC 822, manufactured by METTLER), and an extrapolation glass transition starting temperature that is a temperature at the intersection of a straight line drawn by extending the low temperature-side base line toward the high temperature side and a tangential line drawn at the point where the curve of the stepwise changing part of glass transition has a maximum gradient, was determined in accordance with JIS-K7121 (1987).

<Color Value b>

[0159] The color of chips was measured using a color meter (300A, manufactured by Nippon Denshoku Kogyo K.K.).

[0160] A predetermined amount of chips were put in a glass cell and measured by reflection measurement to determine the value b.

[0161] A smaller value indicates lower yellowness.

<Reduced Viscosity>

[0162] The reduced viscosity was measured at a temperature of 30.0 C.0.1 C. by using an automatic viscometer (Ubbelohde viscometer), Model DT-504, manufactured by Chuo Rika Corp. and using a mixed solvent of phenol and 1,1,2,2-tetrachloroethane in a mass ratio of 1:1. The concentration was precisely adjusted to become 1.00 g/dl.

[0163] The sample was dissolved with stirring at 120 C. for 30 minutes and after cooling, used for the measurement.

[0164] The relative viscosity rel was determined from the flow-through time t.sub.0 of the solvent and the flow-through time t of the solution according to the following formula:

rel=t/t.sub.0 (g.Math.cm.sup.1 sec.sup.1)

[0165] The specific viscosity sp was determined from the relative viscosity rl according to the following formula:

sp=(.sub.0)/.sub.0=rel.sup.1

[0166] The reduced viscosity (reduction viscosity) red was determined by dividing the specific viscosity sp by the concentration c (g/dl) according to the following formula:

red=sp/c

[0167] A higher value indicates a larger molecular weight.

<5% Thermal Weight Loss Temperature>

[0168] Using TG-DTA (SSC-5200, TG/DTA220), manufactured by Seiko Instruments & Electronics Ltd., 10 mg of the sample was placed on an aluminum-made vessel and measured at a temperature rise rate of 10 C./min from 30 C. to 450 C. in a nitrogen atmosphere (nitrogen flow rate: 200 ml/min), and the temperature at which the sample experienced a decrease of 5 mass % was determined.

[0169] A higher temperature indicates that thermal decomposition is less likely to occur.

<Izod Impact Strength>

[0170] Using a mini-max injection molding machine, CS-183MMX, manufactured by Custom Scientific Inc., a test piece having a length of 31.5 mm, a width of 6.2 mm, and a thickness of 3.2 mm was injection-molded at a temperature of 240 to 300 C. and provided with a 1.2 mm-deep notch by a notching machine to obtain a specimen.

[0171] The obtained specimen was measured for the notched Izod impact strength at 23 C. by using a mini-max Izod impact tester, Model CS-183TI, manufactured by Custom Scientific Inc.

[0172] A larger value indicates higher impact strength and lower susceptibility to break.

<Amount of Gas Evolution>

[0173] A polycarbonate resin sample (8 g) vacuum-dried at 100 C. for 5 hours was pressed by a hot press for 1 minute under the conditions of a hot press temperature of 200 to 250 C., a preheating for 1 to 3 minutes and a pressure of 20 MPa by using a spacer having a width of 8 cm, a length of 8 cm and a thickness of 0.5 mm, and then the sample with the spacer was taken out and press-cooled by a water-tube cooling press under a pressure of 20 MPa for 3 minutes to produce a sheet. A sample of 1 cm in width and 2 cm in length was cut out from the sheet. The thickness was 1 mm.

[0174] This sample was measured for the evolved gas by the thermal desorption-gas chromatography/mass spectrometry (TDS-GC/MS). As the measuring apparatus, TDS2 manufactured by GERSTEL was used, and the measurement was performed at a thermal-desorption temperature of 250 C. for 10 minutes by setting the trap temperature to 130 C.

[0175] The sample was placed in a glass chamber, and the gas evolved at 110 C. for 30 minutes with helium at 60 mL/min was collected by a collection tube Tenax-TA.

[0176] HP6890/5973N manufactured by Agilent Inc. was used as GC/MS, and HP-VOC: 0.3260 m and 1.8 m df was used as the column. The collection tube was held at 40 C. for 5 minutes and after raising the temperature to 280 C. at 8 C./min, further held at 280 C. for 25 minutes, and the gas evolution was measured. The carrier gas was helium at 1.3 mL/min.

[0177] The amount of gas evolution was determined as the total evolution amount in terms of toluene per unit area, excluding phenol distilling out during production and phenol-derived benzaldehyde.

<Pencil Hardness>

[0178] A surface measuring device, TRIBOGEAR Type 14DR, manufactured by Shinto Scientific Co., Ltd. was used as the measuring apparatus, and the measurement was performed under the following conditions in accordance with JIS K 5600.

[0179] Load: 750 g

[0180] Measuring speed: 30 mm/min

[0181] Measuring distance: 7 mm

[0182] As the pencil, UNI manufactured by Mitsubishi Pencil Co., Ltd. was used.

[0183] As for the pencil hardness, 4H, 3H, 2H, H, F, HB, B, 2B, 3B, and 4B were used.

[0184] The measurement was performed 5 times, and the hardness one rank softer than the pencil hardness causing two or more occurrences of a scratch was taken as the pencil hardness of the material.

<Apparent Density>

[0185] The density before foaming and the density after foaming were measured by the Archimedes method (using a specific gravity measurement kit, room temperature, water solvent) by using a balance, XS204, manufactured by METTLER TOLEDO. Incidentally, this apparent density is hereinafter referred to as density.

<Expansion Ratio 1>

[0186] The ratio [(density before foaming)/(density after foaming)] of the density before foaming to the density after foaming was taken as the expansion ratio.

<Expansion Ratio 2>

[0187] The ratio [(thickness of foam-molded body)/(thickness of mold before expansion of cavity)] of the thickness of foam-molded body to the thickness of mold before expansion of cavity was taken as the expansion ratio.

<Expansion Ratio 3>

(In the Case of Foam Molding by Core-Back Method)

[0188] The ratio [(thickness of foam-molded body)/(thickness of mold before expansion of cavity)] of the thickness of mold before expansion of cavity to the thickness of foam-molded body was taken as the expansion ratio.

(In the Case of Foam Molding by Short-Shot Method)

[0189] The ratio [(thickness of foam-molded body)/(thickness of mold capable of receiving full shot)] of the thickness of foam-molded body to the thickness of mold capable of receiving full shot was taken as the expansion ratio.

<Tensile Test of Resin Before Foam-Molding>

[0190] A tensile test piece having a parallel-part length of 9 mm and a parallel-part diameter of 1.5 mm was injection-molded using the above-described injection molding machine at a temperature of 240 to 300 C. and by performing a tensile test under the conditions of a tensile speed of 1 cm/min by using a tensile tester, Model CS-183TE, manufactured by Custom Scientific Inc., the elongation at yield, the tensile strength at yield, the tensile modulus at yield, and the elongation at break were measured.

[0191] A larger value indicates a higher strength or elongation.

<Tensile Test of Resin After Foam-Molding>

[0192] The foam-molded body was cut into a strip having a length of 63.5 mm and a width of 16 mm by using a sawing machine. At this time, in order to arrange the longitudinal direction of the original foam-molded body to become the length direction of the molded body after cutting, the cutting was performed from the central portion in the width direction of the original foam-molded body and from the portion located at half on the gate side in the length direction. Subsequently, the obtained strip-like molded body was cut using a sample piece preparing machine, Model IDT-3, manufactured by Toyo Baldwin to obtain a dumbbell-shaped test piece having a parallel-part length of 20 mm, a parallel-part width of 8 mm, and a test piece length of 80 mm. The obtained test piece was subjected to a tensile test under the conditions of a tensile speed of 50 mm/min by using a tensile tester, STROGRAPH Model VG10-E, manufactured by Toyo Seiki Seisaku-Sho, Ltd. to measure the elongation at break. A larger value indicates a higher elongation.

<Henry's Constant>

[0193] The resin is thoroughly dried and then pressurized and depressurized at a predetermined temperature (for example, from 180 to 280 C.) by using a molding machine (for example, a desktop molding press manufactured by Imoto Machinery Co., Ltd.) to prepare a bubbleless test piece (for example, 20 mm, thickness: from 1 to 3 mm), and the change in mass when carbon dioxide is incorporated into the sample in a carbon dioxide atmosphere at a temperature of 200 C. and a pressure of 5 to 20 MPa is measured using a magnetic suspension balance system (BEL P/O 152, manufactured by RUBOTHERM, Germany), whereby the solubility of carbon dioxide for resin can be determined.

[0194] The gas solubility C (g (carbon dioxide)/g (resin composition) of carbon dioxide for resin determined by the technique above and the pressure P (MPa) were fitted by a least square method to the relational expression C=kP of Henry's law to determine the Henry's constant k.

[0195] Incidentally, in the following Production Examples 1 to 7, isosorbide used for reaction is produced by Roquette Freres or by Sanko Chemical Co., Ltd.; 1,4-cyclohexanedimethanol is produced by Eastman Chemical Co.; diphenyl carbonate is produced by Mitsubishi Chemical Corp.; tricyclodecanedimethanol is produced by Celanese Ltd.; and cesium carbonate, calcium acetate monohydrate and 1,6-hexanediol are produced by Wako Pure Chemical Industries Ltd.

[0196] Also, abbreviations for compounds used in Production Examples 1 to 7 are as follows.

[0197] ISB: isosorbide

[0198] 1,4-CHDM: 1,4-cyclohexanedimethanol

[0199] TCDDM: tricyclodecanedimethanol

[0200] 1,6-HD: 1,6-hexanediol

[0201] DPC: diphenyl carbonate

Production Example 1: Production of Polycarbonate Copolymer (PC-1)

[0202] The copolymer was produced as follows in accordance with the method described in Example 1 of JP-A-2009-161746.

[0203] A reaction vessel was charged with 13.0 parts by mass (0.246 mol) of 1,4-CHDM, 59.2 parts by mass (0.752 mol) of DPC, and 2.2110.sup.4 parts by mass (1.8410.sup.6 mol) of cesium carbonate as a catalyst, per 27.7 parts by mass (0.516 mol) of ISB, and in a nitrogen atmosphere, as a first step of reaction, a heating bath was heated at temperature of 150 C. to dissolve the raw materials, if desired, with stirring (about 15 minutes).

[0204] Subsequently, the pressure was reduced from ordinary pressure to 13.3 kPa (absolute pressure; hereinafter, the same) and while raising the heating bath temperature to 190 C. over 1 hour, phenol occurring was withdrawn out of the reaction vessel.

[0205] After holding the whole reaction vessel at 190 C. for 15 minutes, as a second step, the pressure in the reaction vessel was reduced to 6.67 kPa, and while raising the heating bath temperature was raised to 230 C. over 15 minutes, phenol occurring was withdrawn out of the reaction vessel. The stirring torque of the stirrer was increased and therefore, the temperature was raised to 250 C. over 8 minutes. For removing further occurring phenol, the pressure in the reaction vessel was caused to reach 0.200 kPa or less, and after reaching a predetermined stirring torque, the reaction was terminated. The reaction product obtained was extruded in water to obtain a pellet of Polycarbonate Copolymer (PC-1).

[0206] The Henry's constant of carbon dioxide at 200 C. for the obtained Polycarbonate Copolymer (PC-1) was 3.410.sup.3 g (carbon dioxide)/g (resin composition).Math.MPa, the reduced viscosity was 1.007 dl/g, the glass transition temperature was 124 C., and the color value b was 8.8.

[0207] Furthermore, this Polycarbonate Copolymer (PC-1) was molded at 245 C. and a mold temperature of 90 C. to obtain a test piece (two kinds) for evaluation of mechanical properties. Evaluations of mechanical properties were performed using these test pieces, as a result, the tensile strength at yield was 84 MPa, the tensile modulus at yield was 748 MPa, the elongation at yield was 16%, the elongation at break was 30%, and the Izod impact strength was 227 J/m.sup.2.

[0208] Also, the 5% thermal weight loss temperature of Polycarbonate Copolymer (PC-1) in a nitrogen atmosphere was 344 C. The amount of evolved gas except for a phenol component was 3.7 ng/cm.sup.2, and an evolved gas derived from dihydroxy compounds except for the dihydroxy compound represented by formula (1) was not detected.

Production Example 2: Production of Polycarbonate Copolymer (PC-2)

[0209] Production was performed in the same manner as in Production Example 1 except for changing the added amounts to 19.7 parts by mass (0.363 mol) of ISB, 21.6 parts by mass (0.404 mol) of 1,4-CHDM, 58.8 parts by mass (0.741 mol) of DPC, and 2.1910.sup.4 parts by mass (1.8210.sup.6 mol) of cesium carbonate as a catalyst.

[0210] The Henry's constant of carbon dioxide at 200 C. for the obtained Polycarbonate Copolymer (PC-2) was 3.710.sup.3 g (carbon dioxide)/g (resin composition).Math.MPa, the reduced viscosity was 1.196 dl/g, the glass transition temperature was 101 C., and the color value b was 7.7.

[0211] Furthermore, this Polycarbonate Copolymer (PC-2) was molded at 245 C. and a mold temperature of 80 C. to obtain a test piece (two kinds) for evaluation of mechanical properties. Evaluations of mechanical properties were performed using these test pieces, as a result, the tensile strength at yield was 66 MPa, the tensile modulus at yield was 595 MPa, the elongation at yield was 16%, the elongation at break was 27%, and the Izod impact strength was 293 J/m.sup.2. The 5% thermal weight loss temperature of Polycarbonate Copolymer (PC-2) in a nitrogen atmosphere was 345 C.

Production Example 3: Production of Polycarbonate Copolymer (PC-3)

[0212] The copolymer was produced as follows in accordance with the method described in Example 13 of JP-A-2009-161746.

[0213] A reaction vessel was charged with 15.8 parts by mass (0.211 mol) of TCDDM, 57.4 parts by mass (0.704 mol) of DPC, and 2.1410.sup.4 parts by mass (1.7310.sup.6 mol) of cesium carbonate as a catalyst, per 26.9 parts by mass (0.483 mol) of ISB, and in a nitrogen atmosphere, as a first step of reaction, a heating bath was heated at temperature of 150 C. to dissolve the raw materials, if desired, with stirring (about 15 minutes).

[0214] Subsequently, the pressure was reduced from ordinary pressure to 13.3 kPa over 40 minutes and while raising the heating bath temperature to 190 C. over 40 minutes, phenol occurring was withdrawn out of the reaction vessel.

[0215] After holding the whole reaction vessel at 190 C. for 15 minutes, as a second step, the heating bath temperature was raised to 220 C. over 30 minutes, and 10 minutes after the temperature rise, the pressure in the reaction vessel was reduced to 0.200 kPa or less over 30 minutes to distill out the occurring phenol. The reaction was terminated after reaching a predetermined stirring torque, and the reaction product obtained was extruded in water to obtain a pellet of a polycarbonate copolymer.

[0216] The reduced viscosity of the obtained Polycarbonate Copolymer (PC-3) was 0.640 dl/g, the glass transition temperature was 126 C., and the color value b was 4.6.

[0217] Furthermore, this Polycarbonate Copolymer (PC-3) was molded at 245 C. and a mold temperature of 90 C. to obtain a test piece (two kinds) for evaluation of mechanical properties. Evaluations of mechanical properties were performed using these test pieces, as a result, the tensile strength at yield was 89 MPa, the tensile modulus at yield was 834 MPa, the elongation at yield was 15%, the elongation at break was 76%, and the Izod impact strength was 48 J/m.sup.2.

[0218] Also, the 5% thermal weight loss temperature of Polycarbonate Copolymer (PC-3) in a nitrogen atmosphere was 348 C.

[0219] In addition, the amount of evolved gas except for a phenol component was 4.5 ng/cm.sup.2, and an evolved gas derived from dihydroxy compounds except for the dihydroxy compound represented by formula (1) was not detected. The pencil hardness was F.

Production Example 4: Production of Polycarbonate Copolymer (PC-4)

[0220] Production was performed in the same manner as in Production Example 3 except for changing the added amounts to 25.6 parts by mass (0.333 mol) of TCDDM, 55.8 parts by mass (0.666 mol) of DPC, and 2.0810.sup.4 parts by mass (1.6310.sup.6 mol) of cesium carbonate as a catalyst, per 18.7 parts by mass (0.327 mol) of ISB.

[0221] The reduced viscosity of the obtained Polycarbonate Copolymer (PC-4) was 0.785 dl/g, the glass transition temperature was 110 C., and the color value b was 4.7.

[0222] Furthermore, this Polycarbonate Copolymer (PC-4) was molded at 245 C. and a mold temperature of 90 C. to obtain a test piece (two kinds) for evaluation of mechanical properties. Evaluations of mechanical properties were performed using these test pieces, as a result, the tensile strength at yield was 79 MPa, the tensile modulus at yield was 807 MPa, the elongation at yield was 13%, the elongation at break was 18%, and the Izod impact strength was 58 J/m.sup.2.

[0223] Also, the 5% thermal weight loss temperature of Polycarbonate Copolymer (PC-4) in a nitrogen atmosphere was 349 C.

Production Example 5: Production of Polycarbonate Copolymer (PC-5)

[0224] The copolymer was produced as follows in accordance with the method described in Example 1 of JP-A-2011-111614.

[0225] A polymerization reaction apparatus having a stirring blade and a reflux condenser controlled to 100 C. was charged with ISB, 1,6-HD, DPC adjusted to a chloride ion concentration of 10 ppb or less by distillation purification, and calcium acetate monohydrate in a molar ratio of ISB/1,6-HD/DPC/calcium acetate monohydrate=0.85/0.15/1.00/2.010.sup.6 and thoroughly purged with nitrogen (oxygen concentration: from 0.0005 to 0.001 vol %). Subsequently, heating was performed with a heating medium and when the internal temperature reached 140 C., stirring was initiated. The internal temperature rose to 210 C. in 40 minutes after the initiation of temperature rise and when the internal temperature reached 210 C., the system was controlled to hold this temperature. At the same time, pressure reduction was initiated, and the pressure was reduced to 13.3 kPa in 90 minutes after reaching 210 C. While keeping this pressure, the system was further held for 30 minutes. Phenol vapor occurring as a by-product along with the polymerization reaction was introduced into the reflux condenser at 100 C., a small amount of a monomer component contained in the phenol vapor was returned to the polymerization reactor, and the uncondensed phenol vapor was successively introduced into a condenser at 45 C. and recovered.

[0226] After once restoring atmospheric pressure with nitrogen, the contents oligomerized as above were transferred to another polymerization reaction apparatus having a stirring blade and a reflux condenser controlled to 100 C., and temperature rise and pressure reduction were initiated. An internal temperature of 230 C. and a pressure of 200 Pa were reached in 50 minutes and thereafter, the pressure was reduced to 133 Pa or less over 20 minutes. When a predetermined stirring power was achieved, the pressure was restored with nitrogen, and the contents were withdrawn in a strand form and pelletized by a rotary cutter.

[0227] The reduced viscosity of the obtained Polycarbonate Copolymer (PC-5) was 0.4299 dl/g, the glass transition temperature was 122 C., and the color value b was 12.22.

Production Example 6: Production of Polycarbonate Copolymer (PC-6)

[0228] Production was performed in the same manner as in Production Example 5 except for charging the raw materials in a molar ratio of ISB/1,6-HD/DPC/calcium acetate monohydrate=0.70/0.30/1.00/2.010.sup.6.

[0229] The reduced viscosity of the obtained Polycarbonate Copolymer (PC-6) was 0.4655 dl/g, the glass transition temperature was 86 C., and the color value b was 15.10.

Production Example 7: Production of Polycarbonate (Homopolymer) (PC-7)

[0230] The polymer was produced as follows in accordance with the method described in Example 27 of JP-A-2009-161746.

[0231] A reaction vessel was charged with 59.9 parts by mass (0.592 mol) of DPC and 2.2310.sup.4 parts by mass (1.4510.sup.6 mol) of cesium carbonate as a catalyst, per 40.1 parts by mass (0.581 mol) of ISB, and heated with stirring to 150 C. from room temperature to dissolve the raw materials (about 15 minutes).

[0232] Subsequently, the pressure was reduced from ordinary pressure to 13.3 kPa and while raising the temperature to 190 C. over 1 hour, phenol occurring was withdrawn out of the system. After holding the system at 190 C. for 15 minutes, the pressure in the reactor was set to 6.67 kPa, and the heating bath temperature was raised to 230 C. over 15 minutes to remove the occurring phenol. The stirring torque was increased and therefore, the temperature was raised to 250 C. over 8 minutes. For removing further occurring phenol, the degree of vacuum was caused to reach 0.200 kPa or less, and after reaching a predetermined stirring torque, the reaction was terminated. It was tried to extrude the reaction product in water and obtain a pellet, but the reaction product could not be extruded and therefore, was taken out as a lump.

[0233] The Henry's constant of carbon dioxide at 200 C. for the obtained Polycarbonate Copolymer (PC-7) was 2.610.sup.3 g (carbon dioxide)/g (resin composition).Math.MPa, the reduced viscosity was 0.679 dl/g, the glass transition temperature was 160 C., and the color value b was 13.0. As compared with Production Examples 1 to 7, the value b is high, and the polymer was colored brown.

[0234] Furthermore, this Polycarbonate Copolymer (PC-7) was molded at 265 C. to obtain a test piece (two kinds) for evaluation of mechanical properties. Evaluations of mechanical properties were performed using these test pieces, as a result, the tensile strength at yield was 105 MPa, the tensile modulus at yield was 353 MPa, the elongation at yield was 17%, the elongation at break was 31%, and the Izod impact strength was 11 J/m.sup.2. It is seen that as compared with Production Examples 1 to 7, the Izod impact strength was significantly low.

[0235] Also, the 5% thermal weight loss temperature of Polycarbonate Copolymer (PC-7) in a nitrogen atmosphere was 339 C.

Examples 1-1 to 1-6 and Comparative Example 1-1

[0236] Each of the resins obtained in Production Examples 1 to 7 was vacuum-dried at 80 C. for 12 hours and then press-molded at 180 to 230 C. to produce a sheet having a thickness of 1 mm. The produced sheet was cut into a 30-mm square and used as a test piece. The test piece was vacuum-dried at 80 C. for 6 hours and after measuring the density, charged into a pressure vessel at room temperature. The inside of the vessel was purged with carbon dioxide and then pressurized to 10 MPa to impregnate the test piece with carbon dioxide. After passing of 2 hours and 30 minutes, the leak valve of the pressure vessel was opened, and the pressure was gradually reduced to atmospheric pressure. Thereafter, the test piece was taken out from the pressure vessel, and the test piece taken out was dipped in an oil bath heated around +20 C. of the glass transition temperature (Tg) for 1 minute to achieve foaming and then dipped in water, thereby stopping the foaming. The foam-molded body was taken out, and the foam-molded body taken out was dried at 80 C. for 12 hours and then measured for the density.

[0237] The composition of each resin, the glass transition temperature (Tg), the temperature of oil bath used for foam-molding, the difference between oil bath temperature and Tg, the density (g/cm.sup.3), and the expansion ratio are shown in Table 1.

[0238] Incidentally, the expansion ratio is a value obtained by measurement of Expansion Ratio 1.

[0239] The composition of the polycarbonate resin, the molding conditions, and the characteristics of the foam-molded body are shown in Table 2. Incidentally, the Elongation at Break of Polycarbonate Resin is a value obtained by measuring the elongation at break of resin before foam-molding by the method described in the specification.

TABLE-US-00001 TABLE 1 Difference between Tg and Density Oil Bath Oil Bath Before After Expansion Polycarbonate Composition Tg Temperature Temperature Foaming Foaming Ratio Example 1-1 PC-1 ISB:CHDM = 68:32 124 C. 145 C. 21 C. 1.371 0.992 1.38 Example 1-2 PC-2 ISB:CHDM = 47:53 101 C. 125 C. 24 C. 1.304 0.639 2.04 Example 1-3 PC-3 ISB:TCDDM = 70:30 126 C. 145 C. 19 C. 1.353 0.777 1.74 Example 1-4 PC-4 ISB:TCDDM = 50:50 110 C. 125 C. 15 C. 1.298 0.374 3.47 Example 1-5 PC-5 ISB:1,6-HD = 85:15 122 C. 145 C. 23 C. 1.417 1.013 1.4 Example 1-6 PC-6 ISB:1,6-HD = 70:30 86 C. 105 C. 19 C. 1.376 0.392 3.51 Comparative PC-7 ISB = 100 160 C. 180 C. 20 C. 1.438 1.341 1.07 Example 1-1

TABLE-US-00002 TABLE 2 Molding Conditions Amount of Polycarbonate Resin Foaming Foam-Molded Body Elongation Agent Mold Thickness Elongation at Molding Physical Injected Opening of Molded Expansion at Break Temperature Foaming parts by Amount Article Ratio Density Break Kind Composition % C. Agent mass mm mm times g/cm.sup.3 % Example 1-1 PC-1 ISB:CHDM = 68:32 30 250 nitrogen 0.8 2.5 4 2.7 0.487 13.7 Example 1-2 PC-2 ISB:CHDM = 47:53 27 250 nitrogen 0.8 2.5 4 2.7 0.448 5.8 Comparative PC-7 ISB = 100 31 250 nitrogen 0.8 2.5 4 2.7 2.3 Example 1-1

[0240] It is seen from Table 1 that polycarbonate copolymers of Examples 1-1 to 1-6 (a polycarbonate having a structural unit derived from isosorbide and a structural unit derived from other dihydroxy compounds) exhibit as excellent a foaming performance as 1.4 to 3.5 times at a temperature higher by approximately from 15 to 24 C. than the glass transition temperature (Tg). Also, the molded bodies (foam-molded bodies) obtained in Examples 1-1 to 1-6 have excellent mechanical properties.

[0241] On the other hand, in PC-7 (homopolymer of isosorbide) of Comparative Example 1-1, the expansion ratio at a temperature (180 C.) higher by 20 C. than the glass transition temperature (Tg) is 1.07, and it is seen that the foaming performance of the polymer is significantly poor as compared with Examples 1-1 to 1-6.

[0242] The result above is considered to occur because the gas solubility of the copolymer of isosorbide and other dihydroxy compounds was increased as compared with the isosorbide homopolymer.

[0243] Comparative Example 1-1 corresponds to Example 1 or 2 of Patent Document 3 (JP-A-2009-964). In Patent Document 3, the density of Examples 1 and 2 (a foam-molded article of an isosorbide homopolymer) is proved to be 650 kg/m.sup.3 in Example 1 and 590 kg/m.sup.3 in Example 2, but these results are attributable to using a liquefied butane gas having higher solubility for resin than carbon dioxide (paragraph [0098] and [Table 2] in paragraph [0100] of Patent Document 3), unlike Comparative Example 1 in the description of the present invention where carbon dioxide is used as the foaming agent. In this connection, it is seen that among polycarbonates having a structural unit derived from isosorbide, a polycarbonate copolymer having a structural unit derived from other dihydroxy compounds, particularly a polycarbonate copolymer having a glass transition temperature (Tg) in the specific range, can provide for a foam-molded body having such a high expansion ratio as that the density is from 0.374 to 1.013 g/cm.sup.3 even when carbon dioxide lower in the solubility than butane is used as the foaming agent.

[0244] Here, the glass transition temperature (Tg) of the polycarbonate (Component A-1) used in Example 1 of Patent Document 3 is 156 C., and the glass transition temperature (Tg) of the polycarbonate (Component A-2) used in Example 2 is 164 C. (paragraphs [0090] to [0093] of Patent Document 3).

[0245] In this way, it is understood from Patent Document 3 that the polycarbonate having a structural unit derived from isosorbide has a high glass transition temperature (Tg) and its extrusion foam-molding requires a temperature as high as 250 C. On the other hand, in the present invention, among polycarbonates having a structural unit derived from isosorbide, a polycarbonate copolymer having a structural unit derived from other dihydroxy compounds, particularly a polycarbonate copolymer having a glass transition temperature (Tg) in the specific range, is foam-molded and therefore, foam-molding at a low temperature as compared with the isosorbide homopolymer is considered to be able to be performed.

[0246] Also, the glass transition temperature (Tg) of the polycarbonate (Component A-4) in Production Example 4 of Patent Document 3 is 138 C. (paragraph [0095] of Patent Document 3). This Component A-4 is proved to be incapable of uniform foaming at 230 C. (Comparative Example 5 in paragraph [0099] of Patent Document 3). Comparative Example 5 of Patent Document 3 is considered to reveal that the viscosity is low because of such a low glass transition temperature and therefore, the bubble-holding property is bad, making it impossible to perform uniform foaming (that is, the foamability is bad).

[0247] On the other hand, in the present invention, as described above, it has been found that among polycarbonates having a structural unit derived from isosorbide, a polycarbonate copolymer having a structural unit derived from other dihydroxy compounds, particularly a polycarbonate copolymer having a glass transition temperature (Tg) in the specific range, can provide for a foamed body having good gas solubility and impact resistance and being lightweight and excellent in mechanical strength. This fact is unexpected and utterly different from the fact disclosed in Patent Document 3, namely, for example, that among polycarbonates having a structural unit derived from isosorbide, when a polycarbonate having a melt viscosity in the specific range is foam-molded in a specific temperature range, a foam-molded article excellent in the heat resistance and mechanical properties is provided, in other words, among isosorbide homopolymers, a homopolymer having a high glass transition temperature (Tg) requires foam-molding at a high temperature because of its high melt viscosity and bad flowability, involving thermal decomposition of the resin, whereas among isosorbide homopolymers, a homopolymer having a low glass transition temperature (Tg) is incapable of uniform foaming due to its low melt viscosity and poor foamability.

Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-4

Examples 2-1 and 2-2: Foam-Molding of Polycarbonate Copolymer (PC-1)

[0248] The polycarbonate pellet of Production Example 1 was charged into the hopper of a MuCell injection molding machine, J85AD-Mucell, manufactured by JSW, and in the metering process, a physical foaming agent (nitrogen or carbon dioxide) was introduced (injected) inside the cylinder (resin melting part) under pressure as shown in Table 3 to mix molten PC-1 and the physical foaming agent. Subsequently, the mixture was injected into a plate-shaped mold of 1.5 mm (thickness)100 mm (width)180 mm (length) and almost at the same time as the completion of filling (within 0.1 seconds before or after the completion of filling), the movable plate of the mold was retreated (core back) by a predetermined stroke amount (mold opening amount) to perform expansion of the cavity, thereby achieving foam-molding. By cooling the cavity as it is for 60 seconds, a foam-molded body was obtained. In this case, the thickness of mold before expansion of cavity used for calculation of the expansion ratio was 1.5 mm. The time taken from the initiation of injection to the completion of filling was set to 1.0 seconds, and the time taken to retreat the movable plate of the mold was set to 0.1 seconds. Also, the mold temperature was adjusted to 60 C.

[0249] In Table 3, the expansion ratio is a value obtained by measurement of Expansion Ratio 2.

[0250] The results are shown in Table 3.

Examples 2-3 and 2-4: Foam-Molding of Polycarbonate Copolymer (PC-2)

[0251] Foam-molding was performed in the same manner as in Examples 2-1 and 2-2 except for using Polycarbonate Copolymer (PC-2) of Production Example 2.

[0252] The results are shown in Table 3. Incidentally, in the column of Suitability for Foam-Molding of Table 3, B of Example 2-4 indicates that molding was possible but chipping of molded article or surface roughening was generated in a part of the molded article.

Comparative Examples 2-1 and 2-2: Foam-Molding of Polycarbonate Copolymer (PC-3)

[0253] Foam-molding was performed in the same manner as in Examples 2-1 and 2-2 except for using Polycarbonate Copolymer (PC-3) of Production Example 3.

[0254] The results are shown in Table 3.

Comparative Example 2-3: Foam-Molding of Polycarbonate S2000R (Bisphenol A-Type PC)

[0255] A bisphenol A-type polycarbonate, S2000R, produced by Mitsubishi Engineering-Plastics Corporation was foam-molded in the same manner as in Examples 2-1 and 2-2. The obtained molded body particularly at the end part on the downstream side of the molten resin inflow had resin chipping or surface roughening presumed to be attributable to gas escape, and this was observed almost throughout the molded article. Thus, the molded article could not withstand practical use.

[0256] The results are shown in Table 3.

Comparative Example 2-4: Foam-Molding of Polycarbonate 7022IR (Bisphenol A-Type PC)

[0257] A bisphenol A-type polycarbonate, 7022IR, produced by Mitsubishi Engineering-Plastics Corporation was foam-molded in the same manner as in Examples 2-1 and 2-2. The obtained molded body particularly at the end part on the downstream side of the molten resin inflow had resin chipping or surface roughening presumed to be attributable to gas escape, and this was observed almost throughout the molded article. Thus, the molded article could not withstand practical use.

[0258] The results are shown in Table 3.

[0259] Criteria for evaluation of Suitability for Foam-Molding:

[0260] A: The foamed article was free of chipping or surface roughening, and molding was possible.

[0261] B: Molding was possible, but chipping of molded article or surface roughening was generated in a part of the molded article.

[0262] C: Chipping of molded article or surface roughening was generated in the molded article, and molding was impossible.

TABLE-US-00003 TABLE 3 Polycarbonate Resin Molding Conditions Henry's Amount of Molded Body Constant Foaming Thickness g (carbondioxide)/g Molding Agent Mold of (resin Temper- Physical Injected Opening Suitability Molded Expansion composition) .Math. ature Foaming parts by Amount for Foam- Article Ratio Kind Composition MPa C. Agent mass mm Molding mm times Example 2-1 PC-1 ISB:CHDM = 68:32 3.4 10.sup.3 250 nitrogen 0.8 3 A 4.5 3 Example 2-2 PC-1 ISB:CHDM = 68:32 3.4 10.sup.3 250 carbon 1.7 6 A 7.5 5 dioxide Example 2-3 PC-2 ISB:CHDM = 47:53 3.7 10.sup.3 250 nitrogen 0.8 1.5 A 3 2 Example 2-4 PC-2 ISB:CHDM = 47:53 3.7 10.sup.3 250 nitrogen 0.8 3 B 4.5 3 Comparative PC-3 ISB = 100 2.6 10.sup.3 250 nitrogen 0.8 3 A 4.5 3 Example 2-1 Comparative PC-3 ISB = 100 2.6 10.sup.3 250 nitrogen 0.8 6 A 7.5 5 Example 2-2 Comparative S2000R BPA-PC 3.5 10.sup.3 300 carbon 1.7 3 C Example 2-3 dioxide Comparative 7022IR BPA-PC 3.5 10.sup.3 300 nitrogen 0.8 3 C Example 2-4

Examples 3-1 and 3-2: Foam-Molding (Core-Back Method) of Polycarbonate Copolymer (PC-1)

[0263] The polycarbonate pellet of Production Example 1 was charged into the hopper of a MuCell injection molding machine, J85AD-Mucell, manufactured by JSW, and in the metering process, a physical foaming agent (nitrogen or carbon dioxide) was introduced (injected) inside the cylinder (resin melting part) under pressure as shown in Table 4 to mix molten PC-1 and the physical foaming agent. In all of Examples and Comparative Examples, the metering stroke was set to a value for receiving a full shot when injected into a plate-shaped mold of 1.5 mm (thickness)100 mm (width)180 mm (length). Subsequently, the mixture was injected into a plate-shaped mold of 1.5 mm (thickness)100 mm (width)180 mm (length) and almost at the same time as the completion of filling (within 0.1 seconds before or after the completion of filling), the movable plate of the mold was retreated (core back) by a predetermined stroke amount (mold opening amount) to perform expansion of the cavity, thereby achieving foam-molding. By cooling the cavity as it is for 60 seconds, a foam-molded body was obtained. In this case, the thickness of mold before expansion of cavity used for calculation of the expansion ratio was 1.5 mm. The time taken from the initiation of injection to the completion of filling was set to 1.0 seconds, and the time taken to retreat the movable plate of the mold was set to 0.1 seconds. Also, the mold temperature was adjusted to 60 C.

[0264] The results are shown in Table 4. Incidentally, in the core-back method, Mold Thickness in the Table indicates the thickness of mold before expansion of cavity.

[0265] Also, in Table 4, the expansion ratio is a value obtained by measurement of Expansion Ratio 3.

Examples 3-3 and 3-4: Foam-Molding (Core-Back Method) of Polycarbonate Copolymer (PC-2)

[0266] Foam-molding was performed in the same manner as in Examples 3-1 and 3-2 except for using Polycarbonate Copolymer (PC-2) of Production Example 2.

[0267] The results are shown in Table 4. Incidentally, in the column of Suitability for Foam-Molding of Table 4, B of Example 3-4 indicates that molding was possible but chipping of molded article or surface roughening was generated in a part of the molded article.

Comparative Examples 3-1 and 3-2: Foam-Molding (Core-Back Method) of Polycarbonate (PC-3)

[0268] Foam-molding was performed in the same manner as in Examples 3-1 and 3-2 except for using Polycarbonate (PC-3) of Production Example 3.

[0269] The results are shown in Table 4.

Comparative Example 3-3: Foam-Molding (Core-Back Method) of Polycarbonate S2000R (Bisphenol A-Type PC)

[0270] A bisphenol A-type polycarbonate, S2000R, produced by Mitsubishi Engineering-Plastics Corporation was foam-molded in the same manner as in Examples 3-1 and 3-2. The obtained molded body particularly at the end part on the downstream side of the molten resin inflow had resin chipping or surface roughening presumed to be attributable to gas escape, and this was observed almost throughout the molded article. Thus, the molded article could not withstand practical use.

[0271] The results are shown in Table 4.

Comparative Example 3-4: Foam-Molding (Core-Back Method) of Polycarbonate 7022IR (Bisphenol A-Type PC)

[0272] A bisphenol A-type polycarbonate, 7022IR, produced by Mitsubishi Engineering-Plastics Corporation was foam-molded in the same manner as in Examples 3-1 and 3-2. The obtained molded body particularly at the end part on the downstream side of the molten resin inflow had resin chipping or surface roughening presumed to be attributable to gas escape, and this was observed almost throughout the molded article. Thus, the molded article could not withstand practical use.

[0273] The results are shown in Table 4.

Examples 3-5 and 3-6: Foam-Molding (Short-Shot Method) of Polycarbonate Copolymer (PC-1)

[0274] The polycarbonate pellet of Production Example 1 was charged into the hopper of a MuCell injection molding machine, J85AD-Mucell, manufactured by JSW, and in the metering process, a physical foaming agent (nitrogen or carbon dioxide) was introduced (injected) inside the cylinder (resin melting part) under pressure as shown in Table 4 to mix molten PC-1 and the physical foaming agent. Subsequently, the mixture was injected into a plate-shaped mold of thickness shown in Table 4100 mm (width)180 mm (length) and cooled as it is for 60 seconds to obtain a foam-molded body. This is foam molding by a method of receiving a short shot while leaving an unfilled part in the mold, and filling the unfilled part by an expansion force due to foaming of the foaming agent to perform molding (short-shot method). In this case, the thickness of mold capable of receiving full shot used for calculation of the expansion ratio was 1.5 mm. The time taken from the initiation of injection to the completion of filling was set to 1.0 seconds. Also, the mold temperature was adjusted to 60 C.

[0275] The results are shown in Table 4. Incidentally, in the column of Suitability for Foam-Molding of Table 4, C of Example 3-6 indicates that foam-molding was possible but the filling amount of the unfilled part by an expansion force due to foaming of the foaming agent was insufficient and in the foam-molded body, the resin was short of filling the end part on the downstream side of the molten resin inflow.

Examples 3-7 and 3-8: Foam-Molding (Short-Shot Method) of Polycarbonate Copolymer (PC-2)

[0276] Foam-molding was performed in the same manner as in Examples 3-5 and 3-6 except for using Polycarbonate Copolymer (PC-2) of Production Example 2.

[0277] The results are shown in Table 4. Incidentally, in the column of Suitability for Foam-Molding of Table 4, C of Example 3-8 indicates that foam-molding was possible but the filling amount of the unfilled part by an expansion force due to foaming of the foaming agent was insufficient and in the foam-molded body, the resin was short of filling the end part on the downstream side of the molten resin inflow.

[0278] Criteria for evaluation of Suitability for Foam-Molding:

[0279] A: The foamed article was free of chipping or surface roughening, and molding was possible.

[0280] B: Molding was possible, but chipping of molded article or surface roughening was generated in a part of the molded article.

[0281] C: Chipping of molded article or surface roughening was generated in the molded article, and molding was impossible.

TABLE-US-00004 TABLE 4 Polycarbonate Resin Amount of Foaming Agent Foaming Mold Thickness Physical Injected Method Thickness Opening Suitability of Molded Temperature Foaming parts by core-back of Mold Amount for Foam- Article Expansion Kind Composition C. Agent mass method mm mm Molding mm Ratio Example 3-1 PC-1 ISB:CHDM = 250 nitrogen 0.8 core-back 1.5 3 A 4.5 3 68:32 method Example 3-2 PC-1 ISB:CHDM = 250 carbon 1.7 core-back 1.5 6 A 7.5 5 68:32 dioxide method Example 3-3 PC-2 ISB:CHDM = 250 nitrogen 0.8 core-back 1.5 1.5 A 3 2 47:53 method Example 3-4 PC-2 ISB:CHDM = 250 nitrogen 0.8 core-back 1.5 3 B 4.5 3 47:53 method Comparative PC-3 ISB = 100 250 nitrogen 0.8 core-back 1.5 3 A 4.5 3 Example 3-1 method Comparative PC-3 ISB = 100 250 nitrogen 0.8 core-back 1.5 6 A 7.5 5 Example 3-2 method Comparative S2000R BPA-PC 300 carbon 1.7 core-back 1.5 3 C Example 3-3 dioxide method Comparative 7022IR BPA-PC 300 nitrogen 0.8 core-back 1.5 3 C Example 3-4 method Example 3-5 PC-1 ISB:CHDM = 250 carbon 1.7 short-shot 2.4 A 2.4 1.6 68:32 dioxide method Example 3-6 PC-1 ISB:CHDM = 250 carbon 1.7 short-shot 3 C 68:32 dioxide method Example 3-7 PC-2 ISB:CHDM = 250 carbon 1.7 short-shot 1.8 A 1.8 1.2 47:53 dioxide method Example 3-8 PC-2 ISB:CHDM = 250 carbon 1.7 short-shot 2.4 C 47:53 dioxide method

[0282] While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. This application is based on a Japanese patent application filed on Aug. 31, 2011 (Application No. 2011-189681), a Japanese patent application filed on Oct. 26, 2011 (Application No. 2011-235371) and a Japanese patent application filed on Oct. 28, 2011 (Application No. 2011-236746), the content thereof being incorporated herein by reference.

INDUSTRIAL APPLICABILITY

[0283] The molded body of the present invention is not particularly limited in its utilization field and can be used as an industrial material over a wide range of fields. The molded body of the present invention is lightweight and excellent in the impact resistance and therefore, can be suitably used particularly for a building member, a packaging material, a container, a buffer material, an electric/electronic material, an automobile member and the like.