WO1993001230A1

WO1993001230A1 - Foamed polyester sheet and production thereof

Info

Publication number: WO1993001230A1
Application number: PCT/JP1992/000884
Authority: WO
Inventors: Masayuki Kawabe; Masaki Yamamoto
Original assignee: Kanebo, Ltd.
Priority date: 1991-07-12
Filing date: 1992-07-10
Publication date: 1993-01-21
Also published as: JP3107569B2

Abstract

A foamed polyester sheet having uniform microcells and a high foaming ratio. In particular, one containing a polycarbonate or polyarylate resin is excellent in high-temperature stability. The sheet is suitable for applications where high-temperature stability is required, such as a vessel used in a microwave oven.

Description

Description Foamed polyester sheet and its manufacturing method

The present invention relates to a foamed polyester sheet and a method for producing the same. More specifically, the present invention relates to a foamed polyester sheet in which polyester is foamed at a high expansion ratio by uniform fine cells and which has excellent high-temperature stability, and a method for easily producing the same.

Background fields

BACKGROUND ART Conventionally, thermoplastic resin foams such as polyolefin, polyurethane, and polyamide foams have been widely used as heat insulating agents, buffering agents, and packaging materials. Such thermoplastic resin foams are usually produced by a method of mixing air bubbles, a method of using a decomposition gas of a foaming agent, a solvent diffusion method, a method of generating gas by a chemical reaction, and the like. On the other hand, aromatic polyesters, especially polyethylene terephthalate (hereinafter referred to as PET), have excellent mechanical properties, heat resistance, chemical resistance, dimensional stability, etc. Used for goods. In recent years, various foaming agents have been added to these thermoplastic polyesters to form them by foaming (see Japanese Patent Application Laid-Open No. 52-43871), or uniform mixing of PET with polycarbonate or inorganic carbonate. Heating the product to a temperature of 250-350 ^e C, keeping it at that heating temperature until CO ₂ is liberated, and then expanding the reaction mixture (Japanese Patent Publication No. 47-38). Japanese Patent Application Laid-Open No. 875/75 and Japanese Patent Application Laid-Open No. 50-41966 / 1990) have been proposed. However, the former method has disadvantages such as coloring caused by the foaming agent, spots of foaming, and a decrease in mechanical properties.The latter method requires a long reaction time at a high temperature, and the reaction mixture is colored and has poor mechanical properties. There is a drawback that decline is inevitable. In addition, PET containing polyolefin is heated and melted, and the molten resin composition is mixed with an inert gas to generate gas. A method for producing a foam molded article (see Japanese Patent Application Laid-Open No. 2-2866725) has also been proposed. With this method using crystalline PET, uniform and fine bubbles cannot be obtained, and the expansion ratio is as low as 3 times or less.

Disclosure of the invention

An object of the present invention is to provide a foamed polyester sheet. Another object of the present invention is to provide a foamed polyester sheet which is foamed at a high foaming ratio by uniform and fine cells.

Still another object of the present invention is to provide a foamed polyester sheet which is lightweight and exhibits excellent mechanical performance.

Still another object of the present invention is to provide a foamed polyester sheet having excellent high-temperature stability and suitable for use as, for example, a container for an electronic range.

Still another object of the present invention is to provide a production method capable of industrially easily producing the above-mentioned expanded polyester sheet of the present invention.

Still other objects and advantages of the present invention will be apparent from the following description.

According to the present invention, the above objects and advantages of the present invention are:

(a) 100 parts by weight of an amorphous polyester copolymer

as well as

(b) at least one foam nucleating agent selected from the group consisting of glass, silica, talc and mica;

This is achieved by a foamed polyester sheet (hereinafter, referred to as a first foamed polyester sheet) characterized by comprising a resin composition (hereinafter, referred to as a first resin composition).

The amorphous polyester copolymer (a) used in the present invention is obtained by polycondensation of a dicarboxylic acid component and a glycol component by a known method, and a dicarboxylic acid used as an acid component. Means that more than 55 mol% of it is occupied by one kind of aromatic dicarboxylic acid. Preferably, the main component of the dicarboxylic acid is terephthalic acid. Other dicarboxylic acids besides terephthalic acid can be used, but these are preferably kept to less than 45 mol% of the acid component. Such other dicarboxylic acids include, for example, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 27-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 14-cyclohexanedicarboxylic acid, diphenic acid 2,4'-dicarboxylic acid, 3,3,1-dimethyldiphenyl 4,4'-dicarboxylic acid, dimeric acid and the like. These other dicarboxylic acids may be used alone or in combination of two or more.

Similarly, 55% by mol or more of the daricol component is preferably occupied by one kind of joule, and the diol as the main component is more preferably ethylene glycol. Other diol components can be used, but it is preferable to keep these to less than 45 mol% of the diol component. Such other diols include, for example, diethylene glycol, triethylene glycol, neoventil glycol, hexamethylene glycol, bisphenol A, bis-1-hydroxyethoxybisphenol A, cyclohexanedimethanol, bis One example is S-hydroxyethoxybisphenol S. These other diols may be used alone or in combination of two or more.

The amorphous polyester copolymer used in the present invention is generally a polyester copolymer having a crystallinity of 10% or more, and preferably 5% or less. Preferred examples thereof include terephthalic acid and ethylene glycol. When polycondensation is carried out by a known method, an amorphous polyester resin obtained by copolymerizing a dicarboxylic acid and / or a diol component in an amount of 30 to 50 mol% as a third component is exemplified. Excellent in color and color. Particularly used third components are isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, Dicarboxylic acids such as dimer monoacid, 1,4-cyclohexanedimethanol, neopentyl glycol, diethylene glycol, bis-S-hydroxyethoxy ethoxybisphenol A, bis-1- / 5-hydroxyethoxy ethoxy bisphenol S, Diols such as bisphenol A are preferred.

The amorphous polyester copolymer (a) used in the present invention preferably has a melt viscosity at the flow start temperature of 8,000 or more, more preferably 20,000 or more. If the melt viscosity is less than 8,000 voids, the size and distribution of the bubbles are difficult to be uniform, and sometimes the gas separates from the molten resin and escapes. The flow start temperature was determined by using the equipment described in JISK-7210-1976, when the load was 500 kgf and the rate of temperature rise was 1 (TCZmin.). The temperature was measured.

The intrinsic viscosity of the amorphous polyester copolymer is preferably 0.6 or more, more preferably 0.7 to 1.0. If the intrinsic viscosity is less than 0.6, the size and distribution of the bubbles are difficult to be uniform, and sometimes the gas separates from the molten resin and may escape.

The foam nucleating agent (b) used in the present invention is glass, tanolek, silica and mica. These are lighter in weight than metals, are inexpensive because they are mass-produced, and are readily available in quality and uniform quality. These nucleating agents may be used alone or in combination of two or more. The addition ratio of the foam nucleating agent is 0.01 to 5 parts by weight per 100 parts by weight of the amorphous polyester copolymer. Foaming nucleating agent (b) If the force is less than 0.01 parts by weight, the polyester cannot be substantially foamed, while if it exceeds 5 parts by weight, the effect as a nucleating agent is saturated. The first resin composition of the present invention may optionally contain a specific foaming aid (e). By containing the specific foaming aid (e), the foaming effect can be further enhanced. Examples of such foaming aids (e) include organic acids, organic acids Ca salt, Zn salt, Mg salt, Ba salt, A1 salt, syrup salt and! ^! ! From salts and esters of organic acids The selected compound is preferred. Two or more of these foaming aids may be used in combination. If the amount of the foaming aid is less than 0.01 part by weight, the effect of containing the foaming aid is small, while if it is more than 5 parts by weight, the physical properties of the obtained foamed molded article tend to deteriorate.

First foamed polyester sheet of the present invention preferably is properly preferred over ^{_{0.0 1~ 1.5 g / cm 3 N}} 0.03~: are provided as a density in the range of L .3 gZcm ^3.

First foamed polyester sheet of the present invention, a feature that is also provided as being foamed Ri by the uniform fine bubbles foamed and high expansion ratio (for example, density in the range of 0.03 to 0.4 cm ^s) Yes

~ i

According to the present invention, there is further provided a foamed polyester sheet having higher temperature stability than the first foamed polyester sheet.

Such a foamed polyester sheet further contains a polycarbonate resin or a polyacrylate resin.

That is, a foamed polyester sheet containing a polycarbonate resin (hereinafter referred to as a second foamed polyester sheet)

(a) 100 parts by weight of an amorphous polyester copolymer,

(b) at least one foam nucleating agent selected from the group consisting of glass, talc, silica and mica 0.01 to 5 parts by weight

as well as

(c) Polycarbonate resin 20 or more: characterized by comprising a resin composition containing L00 parts by weight (hereinafter, referred to as a second resin composition).

In addition, a foamed polyester sheet containing a polyarylate resin (hereinafter, referred to as a third foamed polyester sheet)

(a) 100 parts by weight of an amorphous polyester copolymer,

(b) at least one foam nucleating agent selected from the group consisting of glass, talc, silica and mica 0.01 to 5 parts by weight as well as

(d) Polyarylate resin 15-; L 00 parts by weight

(Hereinafter referred to as a third resin composition).

As the amorphous polyester copolymer (a) and the foam nucleating agent (b) constituting the second and third foamed polyester sheets of the present invention, the above-mentioned first foamed polyester sheet has been described. The same ones are used.

As the polycarbonate resin (c) constituting the second expanded polyester sheet, a resin obtained by a phosgene method or a ester exchange method using bisphenol as a main raw material is preferably used. Examples of the raw material bisphenol include 2,2-bis (4-hydroxyphenyl) propane (described as bisphenol A) and 2,2-bis (4-hydroxyphenyl) ether (described as bisphenol Z). Is done. The average molecular weight of the polycarbonate resin (c) is preferably from 1,000 to: L00,000, more preferably from 10,000 to 100,000. The amount used is 20 to 100 parts by weight, preferably 20 to 50 parts by weight, per 100 parts by weight of the amorphous polyester copolymer (a). If the amount is less than 20 parts by weight, sufficient high-temperature stability cannot be obtained, and if the amount is more than 100 parts by weight, the inherent characteristics of polyester, such as aroma retention and chemical resistance, are impaired.

As the polyarylate resin (d) constituting the third foamed polyester sheet, for example, the following formula

Where X is 1 0-, 1 S—, 1 SO: —, 1 C 0—, Alkyre A down group or a cycloalkylidene group, and scale ¹ ~! ^ ⁸ is the same or different and is a hydrogen atom, a halogen atom or a hydrocarbon group,

Those obtained from bisphenols represented by the following formulas and isophtalic acid and Z or terephthalic acid or a derivative thereof are preferably used.

Examples of the bisphenols include 4,4'-dihydroxydiphenyl ether, bis (4-hydroxy-12-methylphenyl) ether, bis (4-hydroxy-3-cyclophenyl) ether, bis (4 -Hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ketone, bis (4-hydroxyphenyl) methane, bis (4-hydroxy-3-methylphenyl) methane, bis (4-hydroxy-3, 5-dichlorophenyl) methane, bis (4-hydroxy3,5-dibromophenyl) methane, bis (4-hydroxy3,5-difluorophenyl) methane, 1,1-bis (4- Hydroxy phenyl, 2,2-bis (4-hydroxyphenyl 3-methylphenyl) bronokun, 2,2-bis (4-hydroxy) 3-chlorophenyl) propane, 2,2-bis (4-hydroxy-1,3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 1 1,1-bis (4-hydroxyphenyl) butane, bis (4-hydroxyphenyl) phenylmethane, bis (4-hydroxyphenyl) diphenylmethane, bis (4-hydroxyphenyl) 1-4'-methylphenylmethane, 1, 1-bis (4-hydroxyphenyl) 1,2,2,2-trichloroethane, bis (4-hydroxyphenyl) 1 (4'-chlorophenyl) methane, 1,1-bis (4-hydroxyphenyl) Mouth hexane, bis (4-hydroxyphenyl) cyclohexylmethane, 2,2- (4-hydroxyn-butyl) propane and the like. The most frequently used representative is 2,2-bis (4-hydroxyphenyl) propane, This is what is called bisphenol A.

If necessary, a mixture of said bisphenols or bisphenols and small amounts of other divalent compounds, for example dihydroxynaphthalene, hydroquinone such as 2.2-dihydroxydiphenyl, 2,6-dihydroxynaphthalene, hydroquinone, Mixtures of resorcinol, 2,6-dihydroxycyclomouth benzene, 2,6-dihydroxytoluene, 3,6-dihydroxytoluene and the like can be used.

The intrinsic viscosity of the polyarylate resin is preferably 0.4 or more, more preferably 0.6 to 1.0. When the intrinsic viscosity is less than 0.4, the size and distribution of bubbles are difficult to be uniform, and sometimes the gas is separated from the molten resin and may escape. When the intrinsic viscosity is less than 0.4, various physical, mechanical, and chemical properties such as heat resistance, which is a characteristic of the polyarylate resin, tend to be inferior.

It is important that the amount of the polyarylate resin (d) used in the present invention is 15 to 100 parts by weight, and 20 to 50 parts by weight per 100 parts by weight of the amorphous polyester copolymer. Is particularly preferred. If the amount is less than 15 parts by weight, sufficient high-temperature stability cannot be obtained, and if the amount is more than 100 parts by weight, the inherent characteristics of polyester, such as fragrance retention and chemical resistance, will be impaired.

The foamed polyester sheet of the present invention has sufficient mechanical strength, but optionally further contains glass fiber as a reinforcing material in an amount of 25 parts by weight or less per 100 parts by weight of the amorphous polyester copolymer (a). be able to.

According to the present invention, the foamed polyester sheet of the present invention comprises:

(1) (A) A combination of 100 parts by weight of an amorphous polyester copolymer and 0.01 to 5 parts by weight of at least one foam nucleating agent selected from the group consisting of glass, talc, silica and mica. ,

(B) Add polycarbonate resin 20 to the combination of (A) above. ~ 100 parts by weight,

Or

(C) a combination of the above (A) and 15 to 100 parts by weight of a polyarylate resin,

To a melt extruder to melt and mix

(2) mixing the resulting molten mixture with an inert gas while in the melt extruder; and

(3) Extrusion from a sheet forming die to produce a foamed polyester sheet,

It can be manufactured by a method characterized by the above.

The first foamed polyester sheet is produced from the combination of the above (A) by the above method, and similarly, the second foamed polyester sheet is produced from the combination of the above (B), and the first foamed polyester sheet is produced from the combination of the above (C). A foamed polyester sheet of No. 3 is produced.

In the above method, in step (1), a combination of any of (A), (B) and (C) is supplied to a melt extruder and melt-mixed. In step (2), an inert gas is mixed into the resulting molten mixture while in a melt extruder. Then, in step (3), a foamed polyester sheet is produced by extruding from a sheet forming die.

The method comprising the steps (1), (2) and (3) can be carried out by a plasticizing extruder or a melt extruder.

These types of screw extruders extrude a molten thermoplastic resin composition containing air bubbles in which an inert gas is uniformly dispersed from a metal die, and continuously form the sheet into a desired shape. In most cases, single screw extruders are used. Force, and in some cases it is desirable to use a twin-screw extruder or a twin-screw extruder that performs essentially the same function.)

The thermoplastic resin composition supplied to the extruder hose is mixed and heated in the solid transfer zone and transferred to the melting zone. Melting zone The melt is kept at a temperature sufficiently higher than the melting point of the molten resin, and melting, suction and discharge and mixing occur simultaneously. The molten resin is conveyed to the melt transfer zone. In the melt transfer zone, an inert gas is injected into the molten resin, and sufficient stirring is applied so that bubbles of the inert gas are uniformly dispersed throughout the molten resin. The resin entering the melt transfer zone from the melt zone is set at a slightly lower temperature and has a higher melt viscosity. This prevents the inert gas from backmixing through the extruder and escaping from the solid phase transfer zone via the hopper. The inert gas may be any gas that does not chemically react with the thermoplastic resin composition at the required elevated processing temperature. It may be liquefied during filling. Some typical examples that can be used include freon gas, nitrogen, carbon dioxide, propane, butane, pentane, hexane, helium, neon, argon and krypton. Nitrogen is usually used as an inert gas for cost saving purposes.

The molten thermoplastic resin composition in the melt transfer zone is usually fed to a metering pump and finally extruded from a sheet forming die. The metering pump and sheet forming die are kept at a temperature lower than the temperature of the barrel surrounding the melt transfer zone to minimize bubble breakage and diffusion of the inert gas in the thermoplastic. Have been. Upon exiting the sheet forming die, the sheet extrudate expands to a level that depends on the temperature of the melt, the ratio of die length to opening, and the shear stress at the die wall. In some cases, it may be desirable to use a circular die to extrude a slit oven and a tube that can be thermoformed. The produced expanded polyester sheet is cooled without stretching by air cooling or water cooling or passing through a chill roll. The foamed polyester sheet thus produced is generally amorphous.

In the above method, the foam nucleating agent and the foam nucleating agent used in some cases are not supplied directly to the step (1), but are melt-mixed with the amorphous polyester copolymer in advance to obtain the amorphous polyester. Copolymerization It can also be dispersed uniformly in the body and beretized for use.

The expanded polyester sheet can be thermoformed into a heat-set thin article using a conventional thermoforming device. Such thermoforming methods include:

1. pre-heating the foamed polyester sheet until it is degraded and positioning it in the mold,

2. drawing the preheated sheet onto the heated mold surface,

3. heat setting the formed sheet by leaving the sheet in contact with the heated mold for a time sufficient to partially crystallize;

4. Including the step of removing the molded product from the mold cavity c Example

Hereinafter, the present invention will be described in detail with reference to examples.

The intrinsic viscosity of the polyester resin is 20 in a mixed solvent of phenol Z tetrachloroethane-1Z1. C, measured under the conditions of l.Og / lOOcc.

The melt viscosity of the resin is a value measured with a nozzle diameter lmm and a load of 100 kggZcm2 using Shimadzu Corporation FLOWTE STER (model CFT-500).

The thermal deformation onset temperature was measured in a compression mode of Rigaku TMA (Thermal Mechanical Analyser; TAS-100). In the present invention, a foamed sheet having a thermal deformation initiation temperature of 100 C or more is suitable as having excellent heat resistance.

Example 1

Polyethylene terephthalate resin copolymerized with 1,4-cyclohexanedimethanol at 30 mol% (Intrinsic viscosity of resin 0.7, Flow start temperature 150. Melt viscosity at C 25.000 Voids) 100 parts by weight, talc 0.6 parts by weight Parts and stearyl acid Zn 0.4 parts by weight Was done. The prepared dry blend composition was extruded using an extruder having a screw diameter of 65 mm and a screw LZD of 30. Extruder The rotation speed was set to 100 rpm, the temperature of the melting zone was set to 210 ° C, and the temperature of the die was set to 190. C, and nitrogen gas was injected at a pressure of 40 kgZcm ^{2 from the} vent of the melting zone. At this time, the melt viscosity of the resin in the melting zone is 8,300 vise. Density of the produced foam sheet one DOO 0 - 35 g / cm ⁵ (expansion ratio 3.7 times), the thickness (measured by a micrometer) is 0.5 mm, the size of the bubble 60 to 1 50 m, thermal deformation starting The temperature was 80 ° C.

Example 2

A foamed sheet was produced in the same manner as in Example 1 except that the temperature of the melting zone was 19 (TC and the temperature of the die portion was 160). At this time, the melt viscosity of the resin in the melting zone was 25 , 0 00 Boyes a. density of the manufactured foamed sheet is 0.25 cm ⁵ (expansion ratio 5.2 times), the thickness Hiroyoshi 0.5 mm, the size of the bubbles was 60 to 1 5 0 m.

Example 3

Polyethylene terephthalate resin copolymerized with 40% by mole of isophthalic acid (Intrinsic viscosity of resin 0.7, Flow start temperature 150 ° C) 100 parts by weight, 0.6 parts by weight of talc and stearate Z n 0.4 parts by weight was dry blended. The prepared dry blend composition was extruded using an extruder having a screw size of 65 mm and a screw LZD of 30. The extruder rpm to 1 00 rpm, the temperature of the molten zone 1 8 0 ° C, the temperature of the die portion kept at 1 60 C, pressed with nitrogen gas from the vent of the melting zone 40 k gZc m ² did. At this time, the melt viscosity of the resin in the melting zone is 14,000 vise. The density of the manufactured foam sheet was 0.40 gZ cm: '(expansion ratio 3.3 times), the thickness was 0.5 mm, and the bubble size was 60 to 200 / m.

Comparative Example 1

Polyethylene terephthalate resin (Intrinsic viscosity of resin 0.7, Flow open The melt viscosity 2, 000 Boyes) 1 00 parts by weight of the starting temperature 2 35 ^e C, drove Trend a low density polyethylene and 3 parts by weight. The prepared dry blend composition was extruded using an extruder having a screw diameter of 65 mm and a screw L and D of 30. The extruder rotation speed was 0.100 rpm, the melting zone temperature was 280 ° C, and the die temperature was 260. C, and nitrogen gas was injected at 4 O kg / cm ² from the vent of the melting zone. At this time, the melt viscosity of the resin in the melting zone is 2,900 vise. Density of the produced foam sheet is 0.85 gZc m ^s (expansion ratio 1.6 times), thickness 0.5 mm, the size of the bubbles was filed in 1 0 to 300 m.

Example 4

100 parts by weight of a polyethylene naphthalate resin (intrinsic viscosity of the resin 0.7) copolymerized with 30 mol% of 1,4-cyclohexanedimethanol is 100 parts by weight of a polycarbonate resin having an average molecular weight of 20,000. 0.6 parts by weight of talc and 0.4 parts by weight of zinc stearate were dry blended. The prepared dry blend composition was extruded using an extruder having a screw diameter of 65 mm and a screw LZD of 30. The extruder rpm in l OO r pm, the temperature of the molten zone 2 10 ° C, keeping the temperature of the die portion 190 ^e C, pressed with nitrogen gas at 4 0 k gZcm ² from venting section of the melting zone did. At this time, the melt viscosity of the resin in the melting zone is 9,300 boise. The thickness of the manufactured foamed polyester sheet is 0.5 mm, the size of the cells is 60 ~; L 50 m, the density is 0.35 g / cm- \ The expansion ratio is 3.7 times, and the thermal deformation starting temperature is 14 It was 0 ° C.

Example 5

A foamed polyester sheet was produced in the same manner as in Example 4, except that the blend amount of the polycarbonate resin was changed to 50 parts by weight. At this time, the melt viscosity of the resin in the melting zone is 10,000 vise. The thickness of the produced foam sheet is 0.5 mm, and the size of the bubbles is 60 to 15 0 zm, density 0 .40 gZ cm expansion ratio is 4.2 times, the thermal deformation starting temperature was 1 2 O ^e C.

Example 6

Polyethylene naphthalate resin obtained by copolymerizing 1,4-cyclohexanedimethanol at 30 mol% (intrinsic viscosity of resin 0.7) 100 parts by weight of 2,2-bis (4-hydroxyphenyl) 100 parts by weight of a polyarylate resin, 0.6 part by weight of talc, and 0.4 part by weight of zinc stearate obtained from brono, ozone, isophthalic acid and terephthalic acid (50 mol% each) Dry blended. The prepared dry blend composition was extruded using an extruder having a screw diameter of 65 mm and an LZD of 30 for the screw. The extruder rotation speed was kept at 100 rpm, the temperature of the melting zone was kept at 210 ° C, the temperature of the die was kept at 190 ° C, and nitrogen gas was fed from the melting zone vent at 40 kgZcm. Pressed in with ² . At this time, the melt viscosity of the resin in the melt zone is 9.300 voids. The thickness of the produced foam sheet is 0.5 mm, the size of the bubbles is 60 ~: L 50 m, the density is 0.35 g / cm ^: \ The expansion ratio is 3.7 times, heat The deformation starting temperature was 190 ° C.

Example 7

A foamed sheet was produced in the same manner as in Example 6, except that the amount of the polyarylate resin was changed to 50 parts by weight. At this time, the melt viscosity of the resin in the melting zone is 100,000 voids. The thickness of the manufactured foam sheet is 0.5 mm, the size of the bubbles is 60 ~: L50 / zm, the density is 0.40 g / cmK, the expansion ratio is 4.2 times, and the thermal deformation starting temperature is 1 The temperature was 20 ° C.

Claims

The scope of the claims

1. (a) 100 parts by weight of amorphous polyester copolymer

as well as

(b) A foamed polyester sheet comprising a resin composition comprising at least one kind of foaming nucleating agent selected from the group consisting of glass, silica, talc and mica, in an amount of 0.01 to 5 parts by weight.

2. The sheet according to claim 1, wherein the amorphous polyester copolymer (a) is a copolymer containing terephthalic acid and ethylene glycol as main components.

3. The sheet according to claim 1, wherein the amorphous polyester copolymer (a) has an intrinsic viscosity of at least 0.6.

4. The sheet according to claim 1, further comprising glass fibers in an amount of 25 parts by weight or less per 100 parts by weight of the amorphous polyester copolymer (a).

5. The sheet _{c according} to claim 1, having a density of 0.01 to 1.5 gZ cm ^3.

6. Foaming aid (e) selected from the group consisting of organic acids, organic acid esters and organic acid Ca salts, Zn salts, Mg salts, Ba salts, A1 salts, Pb salts and Mn salts. 2. The sheet according to claim 1, further comprising:

7. (a) 100 parts by weight of an amorphous polyester copolymer,

(b) at least one foam nucleating agent selected from the group consisting of glass, talc, silica and mica, 0.01 to 5 parts by weight; and

(c) A foamed polyester sheet comprising a resin composition containing 20 to 100 parts by weight of a polycarbonate resin.

8. The ho ho according to claim 7, wherein the amorphous polyester copolymer (a) is a copolymer containing terephthalic acid and ethylene glycol as main components.

9. A foaming aid (e) selected from the group consisting of organic acids, organic acid esters and organic acid Ca salts, Zn salts, Mg salts, Ba salts, A1 salts, Pb salts and Mn salts. 8. The sheet according to claim 7, further containing.

10. The sheet according to claim 7, wherein the amorphous polyester copolymer (a) has an intrinsic viscosity of at least 0.6.

11. The sheet according to claim 7, further comprising 25 parts by weight or less of glass fiber per 100 parts by weight of the amorphous polyester copolymer (a).

Shi one of claim 7 12. density indicates 0.01 ~ 1.5 gZc m ³

13. (a) 100 parts by weight of an amorphous polyester copolymer,

(b) at least one foaming nucleating agent selected from the group consisting of glass, talc, silica, and mica; 0.01 to 5 parts by weight; and

(d) Polyarylate resin 15-: A foamed polyester sheet comprising a resin composition containing L00 parts by weight.

14. The article according to claim 13, wherein the amorphous polyester copolymer (a) is a copolymer containing terephthalic acid and ethylene glycol as main components.

15. Organic acids, organic acid esters and organic acid Ca salts, Zn salts,

14. The sheet according to claim 13, further comprising a foaming aid (e) selected from the group consisting of Mg salt, Ba salt, A1 salt, Pb salt and Mn salt.

16. The sheet according to claim 13, wherein the amorphous polyester copolymer (a) has an intrinsic viscosity of at least 0.6.

17. The sheet according to claim 13, further comprising 25 parts by weight or less of glass fiber per 100 parts by weight of the amorphous polyester copolymer (a).

18. density according to claim 1 3, which shows a 0.01 to 1.5 GZcm ³ sheet - and.

19.

(1) (A) 100 parts by weight of an amorphous polyester copolymer, and

At least one foam nucleating agent selected from the group consisting of lath, talc, silica, and mica; a combination of 0.01 to 5 parts by weight;

(B) a combination of the combination of the above (A) and 20 to 100 parts by weight of a polycarbonate resin, or

(C) Combination of (A) above and polyarylate resin 15 ~

A combination of 100 parts by weight,

To a melt extruder to melt and mix

(3) Extrusion from a sheet forming die to produce a foamed polyester sheet,

A method for producing a foamed polyester sheet, comprising:

20. The sheet according to claim 19, wherein the amorphous polyester copolymer (a) is a copolymer containing terephthalic acid and ethylene glycol as main components.

21. The method of claim 19, wherein the amorphous polyester copolymer used in step (1) has a melt viscosity of at least 8,000 at the onset flow temperature.

22. In step (1), organic acid, organic acid ester and organic acid Ca salt, Zn salt, Mg salt, Ba salt, A1 salt,? Salt and! 20. The method according to claim 19, further comprising supplying a foaming aid selected from the group consisting of ^^ salts.