JP3061424B2 - Method for producing saturated polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a saturated polyester, and more particularly, to a method for producing a saturated polyester capable of stably supplying a saturated polyester excellent in mechanical strength and heat resistance as a raw material for molding. About the method.

[0002]

BACKGROUND OF THE INVENTION Saturated polyester is widely used in bottles and the like as a plastic material instead of glass, because its molded product has excellent transparency and gas barrier properties.

By the way, such a saturated polyester liquid-phase polymerized product is supplied as chips at the time of molding, but when the saturated polyester is a liquid-phase polymerized product, the chips may adhere to each other in a supply section of a molding machine. In some cases, it was not supplied stably. When the chips are stuck in this way, the supply stability of the molding raw material is reduced, and a biting failure occurs, or bubbles are involved, which often hinders the molding.

[0004] Saturated polyester used as a bottle material has heat resistance that does not cause thermal deformation of the bottle even when filled at a high temperature that can sterilize juice and the like.
Further, for carbonated beverages, mechanical strength that does not break due to internal pressure is required. For this purpose, generally, a solid-phase polymerized product obtained by increasing the molecular weight by subjecting a liquid-phase polymerized product to solid-phase polymerization is used. However, in this case, there are disadvantages that it takes much time and the cost is greatly increased.

The present inventors have conducted intensive studies on a method capable of producing a solid-phase polymerized product of a saturated polyester at a low cost, which can be stably supplied as a molding raw material and has excellent heat resistance and mechanical strength. A chip made of a saturated polyester obtained by liquid-phase polycondensation is subjected to a shearing treatment and then subjected to solid-state polymerization, whereby the solid-state polymerization time can be shortened, and the above-described requirements are satisfied. The inventors have found that a saturated polyester can be obtained, and have completed the invention.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above prior art, and can be stably supplied as a molding material, has excellent moldability, and has excellent heat resistance and mechanical strength. It is an object of the present invention to provide a method for producing a saturated polyester capable of efficiently producing a solid-phase polymerized product of a saturated polyester at low cost.

[0007]

SUMMARY OF THE INVENTION The process for producing a saturated polyester according to the present invention comprises a liquid phase polycondensation step of producing a saturated polyester by polycondensing a dicarboxylic acid and a hydroxy compound in a liquid phase; After shaping the saturated polyester obtained in the above into chips, a shearing treatment step of roughening the chip surface by subjecting the chips to a shearing treatment,
The method comprises the steps of: supplying a chip made of the saturated polyester subjected to the shearing treatment to a solid-state polymerization reactor and further polymerizing the chip.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the method for producing a saturated polyester according to the present invention will be specifically described. In the present invention, first, a dicarboxylic acid and a hydroxy compound are polycondensed in a liquid phase to produce a saturated polyester.

Examples of such a saturated polyester include polyethylene terephthalate, polyethylene naphthalate and saturated polyesters such as the following copolymerized polyesters (1) to (7). Hereinafter, these saturated polyesters will be described more specifically together with the raw materials of dicarboxylic acid and hydroxy compound.

[0010] In the polyethylene terephthalate present invention, the production of polyethylene terephthalate by a dicarboxylic acid consisting of terephthalic acid or an ester-forming derivative thereof, to a hydroxy compound consisting of ethylene glycol or its ester-forming derivative thereof polycondensation. At this time, another dicarboxylic acid and / or another hydroxy compound may be used in an amount of 20 mol% or less.

The dicarboxylic acids which may be used in addition to terephthalic acid or its ester-forming derivatives include, specifically, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid and the like. And aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid and decanedicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid.

Examples of the hydroxy compound which may be used in addition to ethylene glycol or its ester-forming derivative include, specifically, fats such as trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, dodecamethylene glycol and the like. Alicyclic glycols such as aliphatic glycols and cyclohexanedimethanol; bisphenols; hydroquinone; and aromatic diols such as 2,2-bis (4-β-hydroxyethoxyphenyl) propane.

[0013] In the polyethylene naphthalate present invention, a 2,6-naphthalene dicarboxylic acid, and ethylene glycol, to produce polyethylene naphthalate by polycondensation. In the polycondensation, a dicarboxylic acid other than 2,6-naphthalenedicarboxylic acid and a hydroxy compound other than ethylene glycol may be used in an amount of less than 40 mol%.

Such dicarboxylic acids include terephthalic acid, isophthalic acid, 2,7-naphthalenedicarboxylic acid,
2,5-naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-
Diphenyl sulfone dicarboxylic acid, 4,4'-diphenoxyethane dicarboxylic acid, aromatic dicarboxylic acid such as dibromoterephthalic acid, adipic acid, azelaic acid, sebacic acid, aliphatic dicarboxylic acid such as decane dicarboxylic acid, 1,
Examples thereof include alicyclic dicarboxylic acids such as 4-cyclohexanedicarboxylic acid, cyclopropanedicarboxylic acid, and hexahydroterephthalic acid, and hydroxycarboxylic acids such as glycolic acid, p-hydroxybenzoic acid, and p-hydroxyethoxybenzoic acid.

Examples of the hydroxy compound include propylene glycol, trimethylene glycol, diethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol, neopentylene glycol, p-xylene glycol, 1,4-cyclohexanedimethanol. , Bisphenol A, p, p-diphenoxysulfone, 1,4-bis (β-hydroxyethoxy) benzene, 2,2-bis (p-β-hydroxyethoxyphenol) propane, polyalkylene glycol, p-phenylenebis ( Dimethylsiloxane), glycerin and the like.

In addition to the above-mentioned dicarboxylic acids and hydroxy compounds, small amounts of polyfunctional compounds such as trimesic acid, trimethylolethane, trimethylolpropane, trimethylolmethane, pentaerythritol, etc.
It may be used in an amount of at most mol%.

Further, a monofunctional compound such as benzoylbenzoic acid, diphenylsulfonemonocarboxylic acid, stearic acid, methoxypolyethylene glycol, phenoxypolyethylene glycol may be used in a small amount, for example, 2 mol% or less.

In the polyethylene naphthalate obtained by the present invention, the constitutional unit consisting of ethylene-2,6-naphthalate is at least 60 mol%, preferably at least 80 mol%,
More preferably, it is present in an amount of 90 mol% or more.

Copolymer Polyester (1) In the present invention, the copolymer polyester is obtained by polycondensing a dicarboxylic acid containing terephthalic acid and isophthalic acid with a hydroxy compound containing ethylene glycol.
(1) is manufactured.

As such a dicarboxylic acid, terephthalic acid is 85 to 99.5 mol%, preferably 90 to 99.
Isophthalic acid in an amount of 0.5 to 15
It is desirable to use it in an amount of from 0.5 to 10 mol%, preferably from 0.5 to 10 mol%.

In addition to the above dicarboxylic acids, other dicarboxylic acids other than terephthalic acid and isophthalic acid may be used in an amount not impairing the properties of the obtained copolymerized polyester (1), for example, 1 mol% or less.

Examples of such other dicarboxylic acids include phthalic acid, 2-methylterephthalic acid, and 2,6-naphthalenedicarboxylic acid. In addition, as the hydroxy compound, in addition to ethylene glycol as described above,
Other hydroxy compounds may be used in an amount that does not impair the properties of the copolymerized polyester (1), for example, 1 mol% or less.

Examples of such other hydroxy compounds include 1,3-propanediol, 1,4-butanediol, neopentyl glycol, cyclohexanediol, cyclohexanedimethanol, 1,3-bis (2-hydroxyethoxy) benzene , 1,4-bis (2-hydroxyethoxy) benzene, 2,2-bis (4-β-hydroxyethoxyphenyl)
Propane, bis (4-β-hydroxyethoxyphenyl)
Hydroxy compounds having 3 to 15 carbon atoms such as sulfone can be mentioned.

[0024] In the copolymerized polyester (2) The present invention, produced a dicarboxylic acid, a copolymerized polyester by polycondensation and hydroxy compounds containing ethylene glycol (2) comprising terephthalic acid and 2,6-naphthalene dicarboxylic acid I do.

As such a dicarboxylic acid, terephthalic acid is 80 to 99.5 mol%, preferably 90 to 99.
It is desirable to use 2,6-naphthalenedicarboxylic acid in an amount of 0.5 to 20 mol%, preferably 0.5 to 10 mol%, in an amount of 5 mol%.

In addition to the above-mentioned terephthalic acid and 2,6-naphthalenedicarboxylic acid as the dicarboxylic acid, other dicarboxylic acids may be used in an amount not to impair the properties of the resulting copolymerized polyester (2), for example, 1 mol% or less. An acid may be used.

Examples of such other dicarboxylic acids include isophthalic acid, phthalic acid and 2-methylterephthalic acid. As the hydroxy compound, other than the above-mentioned ethylene glycol, another hydroxy compound may be used in an amount that does not impair the properties of the copolymerized polyester (2), for example, 1 mol% or less.

Examples of such other hydroxy compounds include those similar to the hydroxy compounds described in the section of copolymer (2). Copolymerized polyester (3) In the present invention, a copolymerized polyester is obtained by polycondensing a dicarboxylic acid containing terephthalic acid and adipic acid with a hydroxy compound containing ethylene glycol.
(3) is manufactured.

As such a dicarboxylic acid, terephthalic acid is 85 to 99.5 mol%, preferably 90 to 99.
It is desirable to use adipic acid in an amount of 5 to 15 mol%, preferably 0.5 to 10 mol%, in an amount of 5 mol%.

As the dicarboxylic acid, in addition to the above-mentioned terephthalic acid and adipic acid, copolymerized polyester
Other dicarboxylic acids may be used in an amount that does not impair the characteristics of (3), for example, 1 mol% or less.

Examples of such other dicarboxylic acids include isophthalic acid, phthalic acid, 2-methylterephthalic acid, and 2,6-naphthalenedicarboxylic acid. As the hydroxy compound, other than ethylene glycol, a range that does not impair the properties of the copolymerized polyester (3),
For example, another hydroxy compound may be used in an amount of 1 mol% or less.

Examples of such other hydroxy compounds include those similar to the hydroxy compounds described in the section of the copolymer (1). Copolyester (4) In the present invention, a copolyester (4) is produced by polycondensing a dicarboxylic acid containing terephthalic acid with a hydroxy compound containing ethylene glycol and diethylene glycol.

As such a hydroxy compound, ethylene glycol is contained in an amount of 93 to 98 mol%, preferably 95 to 98 mol%.
~ 98 mol% and diethylene glycol in 2
It is desirable to use it in an amount of ７7 mol%, preferably 2-5 mol%.

As the dicarboxylic acid, other than the above-mentioned terephthalic acid, other dicarboxylic acids may be used in an amount that does not impair the properties of the copolymerized polyester (4), for example, 1 mol% or less.

Examples of such other dicarboxylic acids include isophthalic acid, phthalic acid, 2-methylterephthalic acid, and 2,6-naphthalenedicarboxylic acid. Further, in addition to the above ethylene glycol and diethylene glycol as the hydroxy compound, a structural unit derived from another hydroxy compound is contained in an amount not impairing the properties of the copolymerized polyester (4), for example, 1 mol% or less. It may be.

Examples of such other hydroxy compounds include those similar to the hydroxy compounds described in the section of the copolymer (1). Copolyester (5) In the present invention, a copolyester (5) is produced by polycondensing a dicarboxylic acid containing terephthalic acid with a hydroxy compound containing ethylene glycol and neopentyl glycol.

As the hydroxy compound, ethylene glycol is used in an amount of 85 to 99.5 mol%, preferably 90 to 99.5 mol%, and neopentyl glycol is used in an amount of 0.5 to 15 mol%, preferably 90 to 99.5 mol%. Is desirably used in an amount of 0.5 to 10 mol%.

As the dicarboxylic acid, other than the above-mentioned terephthalic acid, other dicarboxylic acids may be used in a range that does not impair the properties of the copolymerized polyester (5), for example, 1 mol% or less.

Examples of such other dicarboxylic acids include isophthalic acid, phthalic acid, 2-methylterephthalic acid, and 2,6-naphthalenedicarboxylic acid. In addition to the above-mentioned ethylene glycol and neopentyl glycol as the hydroxy compound, other hydroxy compounds may be used in a range that does not impair the properties of the copolymerized polyester (5), for example, 1 mol% or less.

Examples of such other hydroxy compounds include those similar to the hydroxy compounds described in the section of the copolymer (1). Copolyester (6) In the present invention, a dicarboxylic acid containing terephthalic acid and a hydroxy compound containing ethylene glycol and cyclohexanedimethanol are polycondensed to produce a copolymer polyester (6).

Such hydroxy compounds include ethylene glycol in an amount of 85 to 99.5 mol%, preferably 90 to 99.5 mol%, and cyclohexane dimethanol in an amount of 0.5 to 15 mol%, preferably Is 0.5-1
It is desirable to use it in an amount of 0 mol%.

As the dicarboxylic acid, other than the above-mentioned terephthalic acid, other dicarboxylic acids may be used in an amount that does not impair the properties of the copolymerized polyester (6), for example, 1 mol% or less.

Examples of such other dicarboxylic acids include isophthalic acid, phthalic acid, 2-methylterephthalic acid, and 2,6-naphthalenedicarboxylic acid. In addition to the above-mentioned ethylene glycol and cyclohexanedimethanol as the hydroxy compound, other hydroxy compounds may be used in an amount that does not impair the properties of the copolymerized polyester (6), for example, 1 mol% or less.

Examples of such other hydroxy compounds include those similar to the hydroxy compounds described in the section of the copolymer (1). Copolyester (7) In the present invention, a dicarboxylic acid, a hydroxy compound, and a polyfunctional hydroxy compound having at least three hydroxy groups are polycondensed to produce a copolyester (7).

Such dicarboxylic acids include isophthalic acid in an amount of 20 to 100 mol%, preferably 50 to 98 mol%, and terephthalic acid in an amount of 0 to 80 mol%, preferably 0.5 to 50 mol%. %.

As the hydroxy compound, hydroxyethoxyresole is 5-90 mol%, preferably 1%.
0-85 mol%, and ethylene glycol in 1
It is desirable to use it in an amount of 0 to 95 mol%, preferably 15 to 90 mol%.

The polyfunctional hydroxy compound having at least three hydroxy groups is used in an amount of 0.05 to 1.0 mole part, preferably 0.1 to 0.5 mole part per 100 mole parts of dicarboxylic acid.
It is desirable to use it in a molar amount.

Such a polyfunctional hydroxy compound is derived from compounds such as trimethylolmethane, trimethylolethane and trimethylolpropane. Of these, trimethylolpropane is preferably used.

The dicarboxylic acids other than the above-mentioned isophthalic acid and terephthalic acid are derived from other dicarboxylic acids in an amount not to impair the properties of the obtained copolymerized polyester (7), for example, 1 mol% or less. May be used.

Examples of such a dicarboxylic acid include isophthalic acid, phthalic acid, 2-methylterephthalic acid, and 2,6-naphthalenedicarboxylic acid. As the hydroxy compound, other than the above-mentioned hydroxyethoxyresole and ethylene glycol, other hydroxy compounds may be used in an amount not impairing the properties of the copolymerized polyester (7), for example, 1 mol% or less.

Examples of such other hydroxy compounds include those similar to the hydroxy compounds described in the section of the copolymer (1). In the liquid phase polycondensation step according to the present invention, the dicarboxylic acid and the hydroxy compound are polycondensed in a liquid phase to produce a saturated polyester.

In the present invention, such a liquid phase polycondensation step specifically comprises an esterification reaction step and a liquid phase polycondensation step. Specifically, when the obtained saturated polyester is polyethylene terephthalate, for example, the reaction is performed as follows using terephthalic acid as a dicarboxylic acid and ethylene glycol as a hydroxy compound.

An ethylene glycol slurry of terephthalic acid is formed from a mixture of terephthalic acid and 1.02 to 1.4 moles, preferably 1.03 to 1.3 moles, of ethylene glycol per mole of terephthalic acid. The slurry is continuously supplied to the esterification reaction step. The esterification reaction is carried out using a device in which at least two esterification reactors are connected in series, under conditions where ethylene glycol is refluxed, while removing water generated by the reaction outside the system by a rectification column. . The reaction conditions for performing the esterification reaction are as follows.
The temperature is 40 to 270 ° C, preferably 245 to 265 ° C, and the pressure is usually 0.2 to 3 kg / cm ² G, preferably 0.5 to ² kg.
/ Cm ² G, the temperature of the final esterification reaction is usually from 250 to 280 ° C., preferably from 255 to 275 ° C., and the pressure is usually from 0 to 1.5 kg / cm ² G, preferably from 0 to 1.5 kg / cm ² G.
1.3 kg / cm ² G. Therefore, when the esterification reaction is carried out in two stages, the first-stage and second-stage esterification reaction conditions are respectively in the above ranges, and when the esterification reaction is carried out in three or more stages, the second stage The reaction conditions for the esterification reaction from the first stage to the stage immediately before the final stage are those between the above-mentioned first-stage reaction conditions and final-stage reaction conditions. For example, if the esterification reaction is performed in three steps,
The temperature of the second stage esterification reaction is usually 245-275.
° C, preferably from 250 to 270 ° C, and the pressure is usually from 0 to
2 kg / cm ² G and preferably 0.2~1.5Kg / cm ² G.
Although the reaction rates of these esterification reactions are not particularly limited in each stage, it is preferable that the degree of the increase in the esterification reaction rate in each stage is smoothly distributed, and furthermore, the final stage of the esterification reaction is performed. It is usually desirable for the reaction product to reach 90% or more, preferably 93% or more. A low-order condensate is obtained by these esterification steps, and the number-average molecular weight of the low-order condensate is usually
500-5000.

The low-order condensate thus obtained is then continuously supplied to a liquid-phase polycondensation reactor. The reaction conditions of the liquid-phase polycondensation are such that the reaction temperature of the first-stage polycondensation is usually from 260 to 290 ° C, preferably from 265 to 290 ° C, more preferably from 270 to 285 ° C, and the pressure is usually 50 to 250 ° C.
0 to 20 Torr, preferably 200 to 30 Torr, and the temperature of the final polycondensation reaction is usually 270 to 3 Torr.
The temperature is preferably from 275 to 295 ° C, and the pressure is usually from 10 to 0.1 Torr, preferably from 5 to 0.5 Torr.
r.

When the liquid phase polycondensation is carried out in two stages,
The conditions of the polycondensation reaction of the first and second stages are respectively in the above ranges.
The reaction conditions for the liquid-phase polycondensation from the first stage to one stage before the last stage are those between the above-mentioned first-stage reaction conditions and the last-stage reaction conditions. For example, when liquid-phase polycondensation is performed in three stages, the reaction temperature of the second-stage liquid-phase polycondensation is usually 26.
5 to 295 ° C, preferably 270 to 290 ° C, more preferably 270 to 285 ° C, and the pressure is usually 50 to 2T.
orr, preferably 40 to 5 Torr.

The intrinsic viscosity [η] reached in each of the liquid phase polycondensation stages is not particularly limited, but it is preferable that the degree of increase in the intrinsic viscosity in each stage be distributed smoothly.

In the above liquid phase polycondensation step, the esterification reaction can be carried out in the presence of the following basic compound. Such basic compounds include tertiary amines such as trimethylamine, tri-n-butylamine and benzyldimethylamine; and quaternary amines such as tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide and trimethylbenzylammonium hydroxide.
Grade ammonium, lithium carbonate, sodium carbonate, potassium carbonate, sodium acetate and the like.

The method of adding these basic compounds is as follows.
It is not particularly limited, and it may be added to all of the esterification reactors, or may be added to the first or second or subsequent specific reactors.

When the above basic compound is used, the abundance of dioxyethylene terephthalate component units in the main chain forming the obtained polyethylene terephthalate can be kept at a relatively low level.

The above polycondensation reaction is carried out in the presence of a catalyst. Examples of such a catalyst include germanium compounds such as germanium dioxide, germanium tetraethoxide, and germanium tetra n-butoxide; antimony catalysts such as antimonium trioxide; and titanium catalysts such as titanium tetrabutoxide.

Among these catalysts, germanium dioxide compounds are preferably used. Further, the above reaction may be performed in the presence of a stabilizer. Such stabilizers include phosphates such as trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, triphenyl phosphide, trisdodecyl phosphide, tris Phosphites such as nonylphenyl phosphide, acid phosphates such as methyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, dibutyl phosphate, monobutyl phosphate, dioctyl phosphate and phosphoric acid, polyphosphoric acid and the like A phosphorus compound is used.

These catalysts and stabilizers may be used in the above-mentioned esterification reaction stage, or may be supplied to the first-stage polycondensation reactor in the liquid-phase polycondensation stage. In the liquid phase polycondensation step of polyethylene terephthalate as described above, the intrinsic viscosity [η] of polyethylene terephthalate obtained from the final stage polycondensation reactor is usually 0.55 to 0.72 dl / g, preferably 0.57. ~ 0.68
dl / g.

In the case of polyethylene terephthalate, the glass transition temperature is usually 50 to 100 ° C., preferably 60 to 90 ° C.

In the shearing treatment step according to the present invention, first, the saturated polyester obtained in the above liquid phase polycondensation step is cooled and formed into chips. Specifically, a strand obtained by melting is guided to, for example, a water tank, cooled, and cut into a length by a strand cutter to obtain chips.

Next, the polyethylene terephthalate chip obtained as described above is subjected to a shearing treatment to roughen the chip surface. Such a shearing process
For example, it can be performed by applying a shear stress to the chip surface. To apply shear stress to the chip surface, the chips may be agitated, for example, such that the chips rub against each other.

The stirrer used for such a purpose is as follows:
There is no particular limitation as long as it can apply shear stress to the chip.
A blender, a ribbon blender, a tumbler blender, and the like.

The shearing time is usually 3 to 20 minutes. The polyethylene terephthalate chip that has been sheared as described above has a roughened chip surface. The degree of surface roughening is determined by using the surface roughness Ra measured according to JIS B 0601-1982 as an index.

Specifically, the surface roughness Ra is determined as follows. According to the method described in Example 1, after the chip was sheared for a predetermined time, the surface roughness was determined in accordance with the method described in JIS B 0601-1982. The measurement was performed using a Mitutoyo Surf Test 401 surface roughness tester in a constant temperature and humidity room at 23 ° C. and 50%. The range was 25 μm, λc was 0.25 mm, and the measured values were measured three times. The average value is shown.

In the shearing treatment, when the surface roughness of the chip before the shearing treatment is Ra μm and the surface roughness of the chip after the shearing treatment is Ra ′ μm, Ra′−Ra is 0.2 μm.
It is preferable that the thickness is set to be not less than μm.

By performing the shearing treatment on the chip as described above, the chip surface is roughened and the chip surface is crystallized.

In the present invention, by subjecting chips made of saturated polyester to the above-mentioned shearing treatment, the crystallinity of the surface is increased, and the chips are less likely to stick to each other in the next solid phase polymerization step. Therefore, the polymerization temperature in the solid phase polymerization step can be performed at a high temperature without preheating, and the polymerization speed is increased, and the solid phase polymerization can be efficiently performed.

In the solid-phase polymerization step according to the present invention, the chips made of the saturated polyester subjected to the shearing treatment as described above are used.
It is supplied to a solid-state polymerization reactor and further polymerized. The solid phase polymerization step includes at least one stage. In the solid phase polymerization, for example, when the saturated polyester is polyethylene terephthalate, the polymerization temperature is usually 190 to 230 ° C., preferably 195 to 225 ° C., and the pressure is usually 1 kg / cm ² G to 10 T.
The reaction is carried out under an atmosphere of an inert gas such as nitrogen gas, argon gas, carbon dioxide gas, or the like, preferably at normal pressure to 100 Torr.

The saturated polyester polymerized in the solid phase polymerization step as described above is crystalline, and the molded article obtained from this saturated polyester has excellent mechanical strength and excellent heat resistance.

The chips made of the saturated polyester obtained as described above have excellent blocking resistance and can be stably supplied as a raw material during molding. For this reason, the moldability of the molded product is improved.

[0075]

The saturated polyester obtained by the production method according to the present invention is excellent in heat resistance and mechanical strength and, when supplied as a raw material, does not stick to each other and can be molded stably. Machine. For this reason, the moldability of the molded product is also improved.

[0076]

Example 1 Polyethylene terephthalate was obtained by liquid phase polycondensation of terephthalic acid and ethylene glycol. This polyethylene terephthalate had the following physical properties. The intrinsic viscosity [η] is 0.55 dl / g, and the glass transition temperature (Tg) is 75 ° C.

5 kg of this polyethylene terephthalate chip was put into a Henschel type mixer (capacity 9 liters, manufactured by Mitsui Miike Seisakusho Co., Ltd .; model FM10B), and the number of revolutions was 1480 rpm using a standard type blade.
For 10 minutes to perform a shearing treatment. Ra at this time
= 0.84 μm, and Ra′−Ra = 0.43 μm.

The solid-state polymerization was specifically carried out by the following method. A cylindrical stainless steel container having an inner diameter of 22 mm and a height of 80 mm is filled with 60 g of polyethylene terephthalate chips and sealed. This container has a nozzle for venting the inert gas at the bottom, and the inert gas is discharged from the top to the outside of the system.

In the solid-phase polymerization, a sealed stainless steel container filled with a polyethylene terephthalate chip is fixed in a sand bath (aluminum oxide, manufactured by Nippon Parkerai Zinc Co., Ltd.) having a heating device, and nitrogen is used as an inert gas. Perform with ventilation.

The nitrogen used at this time has a dew point of -50 ° C. or less and an oxygen concentration of 20 ppm or less, and is preheated so as to have the same bath temperature as before supplying it to the stainless steel container. Nitrogen is supplied to the stainless steel container at a rate of 200 Nl / hour (standard condition).

The sand bath is made to flow by air so that the temperature of the sand bath is uniform and there is no temperature distribution. The heater of the sand bath is controlled by a program controller so that the bath temperature becomes a predetermined solid-state polymerization temperature.

In a state where the polyethylene terephthalate chip was filled and sealed in the cylindrical stainless steel container as described above,
It is mounted and fixed in a sand bath, the temperature is raised while passing nitrogen at an amount of 200 Nl / h, and the temperature is further maintained at 215 ° C. for 12 hours to carry out a solid phase polymerization reaction.

After the solid-state polymerization reaction, the heating was shut off, the temperature in the sand bath was lowered to 70 ° C. while keeping the nitrogen flow, and then the stainless steel container was taken out of the sand bath, and the intrinsic viscosity of the solid-phase-polymerized polyethylene terephthalate chip was reduced. [Η] is measured. At this time, the intrinsic viscosity [η] is 0.85.
dl / g. Further, the chips after the solid-phase polymerization did not block each other.

[0084]

Example 2 Polyethylene naphthalate was obtained by liquid phase polycondensation of 2,6-naphthalenedicarboxylic acid and ethylene glycol. The physical properties of this polyethylene naphthalate were as follows. Intrinsic viscosity [η] is 0.55 dl / g,
Glass transition temperature (Tg) is 75 ° C, Tm is 267 ° C,
Tc is 215 ° C.

The chip made of polyethylene naphthalate was subjected to a shearing treatment in the same manner as in Example 1. At this time, Ra = 0.14 μm of the chip and Ra ′
-Ra = 0.34 [mu] m.

This chip was subjected to solid-state polymerization in the same manner as in Example 1. At this time, the intrinsic viscosity [η] was 0.69 dl / g. The chips were not blocking each other.

[0087]

Comparative Example 1 The same chips as in Example 1 were subjected to solid-state polymerization in the same manner without shearing. The intrinsic viscosity [η] after the solid-phase polymerization was 0.81 dl / g, and many chips were blocked.

[0088]

Comparative Example 2 The same chip as in Example 2 was processed in the same manner as in Comparative Example 1. The intrinsic viscosity [η] after the solid-state polymerization is 0.
It was 57 dl / g, and there was much blocking between chips, which was worse than Comparative Example 1.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-165911 (JP, A) JP-A-55-111215 (JP, A) JP-A-52-29856 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B29B 9/02 C08G 63/88

Claims (2)

(57) [Claims] 1. A liquid phase polycondensation step for producing a saturated polyester by polycondensing a dicarboxylic acid and a hydroxy compound in a liquid phase, and forming a saturated polyester obtained in the liquid phase polycondensation step into chips. A shearing step of roughening the chip surface by subjecting the chip to a shearing treatment, and supplying the chip made of the saturated polyester subjected to the shearing treatment to a solid-state polymerization reactor for further polymerization. And a process for producing a saturated polyester. 2. The method according to claim 1, wherein the surface roughness of the chip before the shearing treatment is Ra μm;
The chip surface is roughened so that Ra'-Ra becomes 0.2 µm or more when the surface roughness of the chip after the shearing treatment is Ra 'µm. Method for producing saturated polyester.