JPH05239247A - Polyarylate resin foam and its production - Google Patents

Abstract

PURPOSE:To obtain the subject foam containing uniform and fine cells and having excellent high-temperature stability by using a resin composition prepared by mixing a polyarylate resin with a specified foaming nucleator. CONSTITUTION:The objective foam is prepared from a resin composition comprising 100 pts.wt. polyarylate resin and 0.01-5 pts.wt. foaming nucleator selected from the group consisting of glass, silica, talc and mica. An example of the polyarylate resin is a wholly aromatic polyester prepared from a diol component comprising a bisphenol represented by the formula (wherein X is O, S, SO2, CO, alkylene or cycloalkylidene; R<1> to R<8> which may be the same or different from each other are each hydrogen, halogen or a hydrocarbon group) and a dicarboxylic acid component comprising terephthalic acid and/or isophthalic acid.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyarylate resin foam and a method for producing the same. More specifically, it relates to a polyarylate resin foam having uniform fine cells, a high foaming rate, and excellent stability at high temperatures, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, thermoplastic resin foams such as polyolefin, polyurethane and polyamide foams have been widely used as heat insulating agents, cushioning agents and packaging materials. Such thermoplastic resin foams are usually manufactured by a method of mixing bubbles, a method of utilizing a decomposition gas of a foaming agent, a solvent vaporization method, a method of generating a gas by a chemical reaction, or the like.

On the other hand, aromatic polyesters, especially polyethylene terephthalate, are used for fibers, films, injection molded products and the like because of their excellent mechanical properties, heat resistance, chemical resistance, dimensional stability and the like. In recent years, various foaming agents have been added to these thermoplastic polyesters for foam molding (see JP-A-52-43871) or a uniform mixture of polyethylene terephthalate and polycarbonate is heated to a temperature of 250 to 350 ° C. and reacted. Let C
A method has been proposed in which the heating temperature is kept until O ₂ is liberated, and then the reaction mixture is expanded (see Japanese Patent Publication No. 47-38875). However, the former method has drawbacks such as coloring caused by a foaming agent, foaming unevenness, and deterioration of mechanical properties, and the latter method requires a long reaction time at a high temperature, resulting in coloring of reaction mixture and deterioration of mechanical properties. There is an unavoidable drawback. A method has also been proposed in which polyethylene terephthalate mixed with a polyolefin is heated and melted, and an inert gas is mixed into a resin composition in a molten state to produce a foamed molded article (see JP-A-2-286725). With this method, uniform fine bubbles cannot be obtained, and the expansion ratio is low, which is 3 times or less. JP-A-50-41964 and JP-A-50-41966 disclose that polyarylate resin has a polybasic carboxylic acid or its alkali salt or inorganic carbonate as a foaming agent, phosphoric acid as a foaming aid, and the like. Although a method for producing a foam in which a cross-linking agent is added as necessary is described, there is a problem in that the expansion ratio is at most 2 and coloring is remarkable due to decomposition of polyarylate.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyarylate resin foam. Another object of the present invention is to provide a polyarylate resin foam having uniform fine cells and having excellent high temperature stability.

Still another object of the present invention is to provide a polyarylate resin foam which has a high expansion ratio, is lightweight and has excellent mechanical properties.

Still another object of the present invention is to provide a method for producing the above polyarylate resin foam of the present invention.

Further 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 as follows: (a) 100 parts by weight of polyarylate resin and (b) a foam nucleating agent selected from the group consisting of glass, silica, talc and mica. 01-5
It is achieved by a polyarylate resin foam characterized by comprising a resin composition containing parts by weight.

The polyarylate resin (a) used in the present invention has, for example, the following formula (1):

[0009]

[Chemical 2]

A wholly aromatic polyester having bisphenol as a diol component and terephthalic acid and / or isophthalic acid as a dicarboxylic acid component.

In the above formula (1), the alkylene group for X is, for example, methylene (--CH _2- ), 1,1-ethylene (--CH (CH ₃ )-), 2,2-propylene (--C).
(CH _{3) 2} -) and the like may be mentioned as being preferred for. Further, as the cycloalkylidene group of X, for example, cyclohexylidene can be mentioned as a preferable example.

Further, in the above formula (1), R ^{1 to} R ⁸
As the halogen atom of, for example, fluorine, chlorine and bromine can be mentioned as preferable ones. As the hydrocarbon group, for example, an alkyl group can be mentioned as a preferable example.

Examples of the bisphenol represented by the above formula (1) include 4,4'-dihydroxy-diphenyl ether, bis (4-hydroxy-2-methylphenyl) ether, bis (4-hydroxy-3-chlorophenyl) 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
-Hydroxy-3,5-dibromophenyl) methane, bis (4-hydroxy-3,5-difluorophenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxy-) 3-methylphenyl) propane, 2,2-bis (4-hydroxy-3-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3) -Dibromophenyl) propane,
1,1-bis (4-hydroxyphenyl) butane, bis (4-hydroxyphenyl) phenylmethane, bis (4
-Hydroxyphenyl) diphenylmethane, bis (4-
Hydroxyphenyl) -4'-methylphenylmethane,
1,1-bis (4-hydroxyphenyl) -2,2,2-
Trichloroethane, bis (4-hydroxyphenyl)-
(4'-chlorophenyl) methane, 1,1-bis (4-
Hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) cyclohexylmethane, 2,2- (4
-Hydroxy n-butyl) propane and the like. Of these, 2,2-bis (4-hydroxyphenyl) propane, that is, what is called bisphenol A is preferable because it is easily available and gives a wholly aromatic polyester having excellent performance.

The above bisphenols can be used alone or in combination of two or more. As the diol component constituting the polyarylate resin (a) of the present invention, in addition to the bisphenol represented by the above formula (1), other bisphenols can be used together with the bisphenol represented by the above formula (1). Examples of such other bisphenols include dihydroxynaphthalene such as 2,2-dihydroxydiphenyl, 2,6-dihydroxynaphthalene, hydroquinone, resorcinol and 2,2.
Examples thereof include 6-dihydroxychlorobenzene, 2,6-dihydroxytoluene and 3,6-dihydroxytoluene. These other bisphenols can also be used alone or in combination of two or more. Such other bisphenol is preferably used in a ratio of 1 mol or less with respect to 1 mol of the bisphenol represented by the above formula (1).

Examples of the aromatic dicarboxylic acid constituting the polyarylate resin (a) of the present invention include terephthalic acid and isophthalic acid.

Among these, terephthalic acid, isophthalic acid and a mixture thereof are preferable, and a mixture of terephthalic acid and isophthalic acid, for example, a mixture having a molar ratio of terephthalic acid to isophthalic acid of 1: 9 to 9: 1 is more preferable.

As the polyarylate resin (a), the bisphenol represented by the above formula (1) is used as a diol component, and the molar ratio of terephthalic acid to isophthalic acid is 1: 9.
It is particularly preferable to use terephthalic acid and isophthalic acid having a dicarboxylic acid component of ˜9: 1.

The polyarylate resin (a) preferably has an intrinsic viscosity of at least 0.4, and more preferably an intrinsic viscosity of 0.6 to 1.0. Intrinsic viscosity is 0.
If it is less than 4, it is difficult to make the size and distribution of bubbles uniform,
At times, the gas may separate from the molten resin and escape, which is not preferable.

When the intrinsic viscosity is less than 0.4, various physical, mechanical and chemical properties such as heat resistance, which is a characteristic of polyarylate resin, are inferior, which is not preferable.

From the viewpoint of melt viscosity, the polyarylate resin (a) used in the present invention preferably has a melt viscosity at the flow initiation temperature of 8,000 poises or more, and preferably 10,000 poises or more. Is more preferable. If the melt viscosity is less than 8,000 poise, the size and distribution of bubbles are difficult to be uniform, and the gas sometimes separates from the molten resin and is not preferable.

The foam nucleating agent (b) used in the present invention is selected from the group consisting of glass, silica, talc and mica. These foam nucleating agents can be used alone or in combination of two or more. The foam nucleating agent is used in a proportion of 0.01 to 5 parts by weight per 100 parts by weight of the polyarylate resin. When the amount of the foam nucleating agent is less than 0.01 part by weight, the polyester cannot be substantially foamed, while when it is more than 5 parts by weight, the physical properties of the obtained foamed molded product are remarkably deteriorated.

The thermoplastic resin composition used in the present invention can further have a foaming effect by adding a specific foaming aid. Such foaming aids are preferably organic acids, organic acid esters and organic acids Ca, Zn, Mg,
It is selected from the group consisting of Ba, Al, Pb and Mn salts. These foaming aids can be used alone or in combination of two or more.

These foaming assistants are polyarylate resin 1
It is used in a proportion of 0.01 to 5 parts by weight per 00 parts by weight. If the amount of the foaming aid is less than 0.01 part by weight, the effect of using the foaming aid is not substantially exhibited, while if it is more than 5 parts by weight, the physical properties of the obtained foamed molded product are remarkably deteriorated.

The polyarylate resin foam of the present invention may contain the polyethylene terephthalate resin (c) in an amount of 40 parts by weight or less, more preferably 5 to 40 parts by weight, per 100 parts by weight of the polyarylate resin (a), if necessary. You can Moldability is improved by using a polyethylene terephthalate resin together. If it is used in excess of 40% by weight, the heat resistance of the foam tends to decrease.

The polyarylate resin foam of the present invention is preferably 0.01 to 1.5 g / cm ³ , more preferably 0.0.
It is provided with a density in the range of ^{3 to} 1.3 g / cm ³ .

Although the foam of the present invention has sufficient mechanical strength, it may optionally further contain glass fiber as a reinforcing agent in an amount of 25 parts by weight or less per 100 parts by weight of the polyarylate resin (a). .. The foam reinforced with glass fibers exhibits a density of, for example, 0.01 to 1.5 g / cm ³ .

According to the present invention, the polyarylate resin foam of the present invention comprises (1) 100 parts by weight of a polyarylate resin and a foam nucleating agent selected from the group consisting of glass, silica, talc and mica in the range of 0.01-5. Parts by weight are fed to a melt extruder for melt mixing, (2) the resulting mixture in the molten state is mixed with an inert gas while in the melt extruder, and (3) extruded from the molding die to produce the desired mixture. It can be produced by a method characterized in that it produces a polyarylate resin foam in the form.

According to the above method of the present invention, in the step (1), the foaming nucleating agent is 0.01 per 100 parts by weight of polyarylate resin.
~ 5 parts by weight are melt mixed in a melt extruder. The above polyarylate resin has a flow initiation temperature of at least 8,000 poise, more preferably at least 10,
Those exhibiting a melt viscosity of 000 poise are advantageously used.

In the step (1), other components used as necessary can be added and mixed. Examples of such other components include the above-mentioned foaming aid, glass fiber as a reinforcing agent, or polyethylene terephthalate resin.

The method of the present invention can carry out steps (2) and (3) continuously after carrying out step (1), or by carrying out step (1), the polyarylate resin composition is pelletized, for example. Alternatively, the steps (2) and (3) may be carried out after the acquisition.

In the melt extruder, the raw material components of step (1) are mixed and heated in the solid transfer zone and transferred to the melting zone. The melting zone is maintained at a temperature well above the melting point of the molten resin so that melting, suction discharge and mixing occur simultaneously.

Next, in step (2), the molten resin is carried to the melt transfer zone. In the melt transfer zone, an inert gas is pressed into the molten resin, and sufficient agitation is provided so that the 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 therefore the melt viscosity is higher. This prevents the inert gas from back mixing through the extruder and escaping from the solid phase transfer zone via the hopper.

As the inert gas, there is used one which does not react with the resin composition produced in the step (1) and is in a gaseous state when mixed. Examples of such an inert gas include freon gas, nitrogen, carbon dioxide, helium, neon, argon, krypton; and propane, butane,
Aliphatic hydrocarbons such as pentane and hexane can be mentioned. Of these, nitrogen is preferable because of its low cost.

The molten thermoplastic resin composition in the melt transfer zone is typically fed to a metering pump and extruded from the molding die in step (3) to form the desired shape. The metering pump and forming die are maintained at a temperature below the temperature of the barrel surrounding the melt transfer zone to minimize bubble collapse and diffusion of the inert gas in the thermoplastic. Upon exiting the forming die, the extrudate expands to a level that depends on the melt temperature, the die length to open ratio and the shear stress in the die wall.

The forming die can be, for example, a sheet forming die or a circular die. The use of a circular die allows slit opening and thermoforming.
The produced foamed sheet is cooled by air cooling or water cooling or passing through a chilled roll without stretching. The foamed sheet produced in this way is generally amorphous.

As the melt extruder, for example, a single-screw extruder, a twin-screw extruder or another screw extruder can be used.

The foamed sheet can be thermoformed into heat set thin articles using conventional thermoforming equipment.
Such thermoforming methods include: 1. Preheating the foam sheet until it softens and positioning in the mold; 2. The step of drawing the preheated sheet onto the heated mold surface; 3. Heat setting the formed sheet by contacting the sheet with a heated mold for a time sufficient to partially crystallize; The step of removing the molded product from the cavity of the mold is included.

[0038]

The present invention will be described in detail below with reference to examples. The resin intrinsic viscosity is phenol / tetrachloroethane = 1.
It was measured in a mixed solvent of 1/1 at 20 ° C. and 1.0 g / 100 cc. The melt viscosity of the resin is a value measured using a Shimadzu FLOWTESTER (model CFT-500) with a nozzle diameter of 1 mm and a load of 100 kg / cm ² . The thermal deformation start temperature is TMA (Th
ermal Mebanibal Analyzer;
It was measured in the compression mode of TAS-100).

Example 1 Polyarylate resin obtained from 2,2-bis (4-hydroxyphenyl) propane and isophthalic acid and terephthalic acid (each 50 mol%) (resin intrinsic viscosity 0.7) 1
To 100 parts by weight, 0.6 parts by weight of talc, Zn stearate
0.4 parts by weight were blended. The prepared thermoplastic resin composition was extruded using an extruder having a screw diameter of 65 mm and a screw L / D of 30. Extruder speed 10
The temperature of the melting zone was maintained at 210 ° C., the temperature of the die portion was maintained at 190 ° C., the nitrogen gas was injected at 40 kg / cm ² from the vent portion of the melting zone at 0 rpm. At this time, the melt viscosity of the resin in the melting zone was 9,300 poise. The thickness of the produced foamed sheet is 0.5 mm, the size of bubbles is 60 to 150 μm, and the density is 0.35 g / cm ³ ,
The expansion ratio is 3.7 times and the thermal deformation start temperature is 140 ° C.
Met.

Comparative Example 1 A foamed sheet was produced in the same manner as in Example 1 except that a polyethylene terephthalate resin was used instead of the polyarylate resin. At this time, the resin melt viscosity in the melting zone was 8,000 poise. The thickness of the produced foam sheet is 0.5 mm, and the size of bubbles is 60.
˜150 μm, density was 1.00 g / cm ³ , expansion ratio was 1.3 times, and heat deformation start temperature was 80 ° C.

Comparative Example 2 Foaming was carried out in the same manner as in Example 1 except that an amorphous polyester resin (30 mol% 1,4-CHDM copolymerized PET, intrinsic viscosity 0.7) was used in place of the polyarylate resin. The sheet was manufactured. At this time, the resin melt viscosity in the melting zone was 8,300 poise. The thickness of the produced foam sheet is 0.5 mm, and the size of bubbles is 60.
˜150 μm, density was 0.35 g / cm ³ , expansion ratio was 3.7 times, and thermal deformation start temperature was 80 ° C.

[0042]

The polyarylate resin foam of the present invention has uniform and fine cells, has a high expansion ratio, and is excellent in high temperature stability. The foam of the present invention is suitably used for applications requiring high temperature stability such as a container for a microwave oven.

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Claims (13)

[Claims] 1. A resin composition comprising (a) 100 parts by weight of a polyarylate resin and (b) 0.01 to 5 parts by weight of a foam nucleating agent selected from the group consisting of glass, silica, talc and mica. A polyarylate resin foam characterized by the following. 2. A polyarylate resin (a) is represented by the following formula (1): The foam according to claim 1, which is a wholly aromatic polyester containing bisphenol as a diol component and terephthalic acid and / or isophthalic acid as a dicarboxylic acid component. 3. The polyarylate resin (a) contains the bisphenol represented by the above formula (1) as a diol component, and the molar ratio of terephthalic acid to isophthalic acid is 1: 9 to.
The foam according to claim 2, wherein 9: 1 terephthalic acid and isophthalic acid are used as the dicarboxylic acid component. 4. The foam according to claim 1, wherein the polyarylate resin (a) has an intrinsic viscosity of at least 0.4. 5. A polyethylene terephthalate resin (c)
The foam according to claim 1, further comprising 40 parts by weight or less per 100 parts by weight of the polyarylate resin. 6. The foaming aid (d) according to claim 1, further comprising an organic acid, an organic acid ester and a foaming aid (d) selected from the group consisting of Ca, Zn, Mg, Ba, Al, Pb and Mn salts of organic acids. Foam. 7. A glass fiber containing polyarylate resin (a)
The foam according to claim 1, further containing 25 parts by weight or less per 100 parts by weight. 8. The foam according to claim 1, wherein the foam has a density of 0.01 to 1.5 g / cm ³ . 9. The foam according to claim 8, wherein the foam has a density of 0.03 to 1.3 g / cm ³ . 10. The foam is in sheet form.
The foam according to. 11. (1) 100 parts by weight of a polyarylate resin and 0.01 to 5 parts by weight of a foam nucleating agent selected from the group consisting of glass, silica, talc and mica are supplied to a melt extruder and melt-mixed, (2) mixing the resulting molten mixture with an inert gas while in the melt extruder, and (3) extruding from a molding die to produce a polyarylate resin foam in the desired form. A method for producing a polyarylate resin foam characterized by the above. 12. In the step (1), an organic acid, an organic acid ester, and an organic acid of Ca, Zn, Mg, Ba, A.
The method of claim 11, further comprising providing a foaming aid selected from the group consisting of 1, Pb and Mn salts. 13. The polyarylate resin used in step (1) is at least 8,000 at the flow start temperature.
The method of claim 11, wherein the melt viscosity of the poise is indicated.