JP2894850B2 - Method for producing polyethylene naphthalate - 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 polyethylene naphthalate, and more particularly, to subjecting a chip of polyethylene naphthalate obtained by liquid phase polycondensation to a shearing treatment to roughen the chip surface to obtain a chip. The present invention relates to a method for producing polyethylene naphthalate, which has improved anti-blocking properties and can be stably supplied as a molding material.

[0002]

BACKGROUND OF THE INVENTION Polyethylene naphthalate is widely used as a bottle material and the like because it has excellent transparency, excellent gas barrier properties, and excellent mechanical strength.

[0003] By the way, such polyethylene naphthalate is usually supplied as chips at the time of molding. However, in the case of polyethylene naphthalate obtained by liquid phase polycondensation, the chips may stick together due to low crystallinity. Easy to block. For this reason, the supply stability of the raw material chips has been reduced to cause poor biting, and air bubbles have been involved, making molding difficult.

In order to solve such a problem, conventionally,
The raw material polyethylene naphthalate obtained by liquid-phase polycondensation is pre-crystallized by heating and cooling, and then further solid-phase polycondensation to increase the crystallinity of polyethylene naphthalate, producing chips that are difficult to block. Was used.

However, the above-described method includes a pre-crystallization step and a solid-phase polycondensation step, and the solid-state polycondensation step has a long time, so that the production cost tends to be high.

In addition to the above, for example, there is a case where a fluid lubricant is added, or a feeder for stabilizing the supply of the raw material is provided at a feed port of the extruder. However, in such means, in the former case, the transparency of the molded article is lowered by the addition of the fluid lubricant, and in the latter case, the equipment becomes large, which is not preferable in industrial production.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to solve the problems associated with the prior art as described above, and to produce polyethylene naphthalate which can be stably supplied as a raw material chip at the time of molding at a low cost. It is an object of the present invention to provide a method for producing polyethylene naphthalate.

[0008]

SUMMARY OF THE INVENTION The process for producing polyethylene naphthalate according to the present invention is characterized in that a dicarboxylic acid containing 2,6-naphthalenedicarboxylic acid and a hydroxy compound containing ethylene glycol are polycondensed in a liquid phase, and usually have a limiting viscosity. Polyethylene naphthalate having [η] of 0.30 to 0.80 dl / g is produced, and then the polyethylene naphthalate obtained in the liquid-phase polycondensation step is formed into chips, which are then composed of the polyethylene naphthalate. It is characterized in that the chip surface is roughened by subjecting the chip to a shearing treatment.

[0009]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the method for producing polyethylene naphthalate according to the present invention will be specifically described.

In the present invention, first, polyethylene naphthalate is produced by polycondensing a dicarboxylic acid containing 2,6-naphthalenedicarboxylic acid and a hydroxy compound containing ethylene glycol in a liquid phase. At the time of polycondensation, the obtained polyethylene naphthalate should contain a constituent unit composed of ethylene-2,6-naphthalate in an amount of 60 mol% or more, preferably 80 mol%, more preferably 90 mol%. , 2,
It is desirable to use 6-naphthalenedicarboxylic acid and ethylene glycol.

In the present invention, dicarboxylic acids other than 2,6-naphthalenedicarboxylic acid and / or hydroxy compounds other than ethylene glycol may be used in an amount of less than 40 mol%.

The dicarboxylic acids other than 2,6-naphthalenedicarboxylic acid include terephthalic acid, isophthalic acid, 2,7-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, and diphenyl-4,4'-dicarboxylic acid. Acids, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenyl sulfone dicarboxylic acid, 4,4'-diphenoxyethane dicarboxylic acid, aromatic dicarboxylic acids such as dibromoterephthalic acid,
Aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, cyclopropanedicarboxylic acid, hexahydroterephthalic acid, glycolic acid, p-hydroxy Hydroxycarboxylic acids such as benzoic acid and p-hydroxyethoxybenzoic acid can be used.

Examples of the hydroxy compound other than ethylene glycol 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 can be used.

As the hydroxy compound, a polyfunctional compound such as trimesic acid, trimethylolethane, trimethylolpropane, trimethylolmethane, or pentaerythritol may be used in a small amount, for example, 2 mol% or less.

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

In the present invention, such a liquid phase polycondensation step specifically includes an esterification reaction step and a polycondensation reaction step, and includes, for example, 2,6-naphthalenedicarboxylic acid as described above. Specifically, a dicarboxylic acid and a hydroxy compound containing ethylene glycol are used as follows.

The polycondensation reaction is performed 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.

Of these catalysts, germanium dioxide compounds are preferably used. The reaction may be performed in the presence of a stabilizer. Such stabilizers include trimethyl phosphate, triethyl phosphate, triethyl phosphate.
Phosphates such as n-butyl phosphate, trioctyl phosphate, triphenyl phosphate and tricresyl phosphate; phosphites such as triphenyl phosphide, trisdodecyl phosphide and trisnonyl phenyl phosphide; methyl acid Acidic phosphates such as phosphate, isopropyl acid phosphate, butyl acid phosphate, dibutyl phosphate, monobutyl phosphate, dioctyl phosphate, and phosphorus compounds such as phosphoric acid and polyphosphoric acid are used.

These catalysts and stabilizers may be used in the esterification reaction step or may be supplied to the first stage polycondensation reactor in the liquid phase polycondensation step.

A hydroxy compound slurry of dicarboxylic acid is formed from a mixture of dicarboxylic acid and 1.0 to 1.4 moles, preferably 1.03 to 1.3 moles, of hydroxy compound per mole of dicarboxylic 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 the hydroxy compound 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 such that the temperature of the first-stage esterification reaction is usually 210 to 210.
The temperature is 250 ° C., preferably 210 ° -250 ° C., and the pressure is usually 0.2-3 kg / cm ² G, preferably 0.5-2 kg / cm ² G.
And the temperature of the final esterification reaction is usually 2
20 to 260 ° C., preferably 240 to 260 ° C., and the pressure is usually 0 to 1.5 kg / cm ² G, preferably 0 to 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,
When the esterification reaction is carried out in three stages, the temperature of the second stage esterification reaction is usually 215 to 255 ° C, preferably 235 to 255 ° C, and the pressure is usually 0 to 2 kg / g.
cm ² G, preferably 0.2 to 1.5 kg / 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 50
0 to 5000.

The low-order condensate thus obtained is continuously supplied to a polycondensation reactor in the next liquid phase polycondensation step. The reaction conditions of the polycondensation reaction are such that the reaction temperature of the first stage polycondensation is usually 240 to 290 ° C, preferably 240 to 290 ° C.
70 ° C., more preferably 250 to 270 ° C., the pressure is usually 500 to 20 Torr, preferably 200 to 30 Torr, and the temperature of the final stage polycondensation reaction is usually 250 to Torr.
The temperature is 300 ° C., preferably 260 to 290 ° C., and the pressure is usually 10 to 0.1 Torr, preferably 5 to 0.5 Torr.

When the polycondensation reaction 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 polycondensation reaction 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 the polycondensation reaction is performed in three stages, the reaction temperature of the second stage polycondensation reaction is usually 25
0 to 290 ° C, preferably 250 to 280 ° C, more preferably 260 to 280 ° C, and the pressure is usually 50 to 2
rr is preferably 40 to 5 Torr.

The intrinsic viscosity [η] reached in each of these polycondensation reaction steps 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 performed 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 the dioxyethylene terephthalate component unit in the main chain forming the obtained polyethylene terephthalate can be kept at a relatively low level.

In the liquid-phase polycondensation of polyethylene naphthalate as described above, the intrinsic viscosity [η] of polyethylene naphthalate obtained from the final stage polycondensation reactor is usually 0.2 to 0.8 dl / g. Is 0.3-0.7dl /
g.

The intrinsic viscosity [η] is determined as follows. Polyethylene naphthalate was dissolved in o-chlorophenol at a concentration of 1 g / 100 ml,
The solution viscosity was measured using an Ubbelohde capillary viscometer at 0 ° C., and then o-chlorophenol was gradually added to measure the solution viscosity on the low concentration side. η].

The glass transition temperature is usually 80 to 130.
C, preferably 100 to 120C. The polyethylene naphthalate obtained by the liquid phase polycondensation as described above is cooled to produce a chip.

In the present invention, the chip made of polyethylene terephthalate obtained as described above is subjected to a shearing treatment to roughen the chip surface. Such a shearing treatment can be performed, for example, by applying a shearing 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 naphthalate chip that has been subjected to the shearing treatment 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.

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%.
It is preferable that the thickness is set to be not less than μm.

In the present invention, by roughening the chips as described above, the chips are less likely to stick to each other in a step of drying the chips after the shearing treatment.
Blocking is less likely to occur.

As described above, by performing the shearing treatment on the chip, the chip surface is roughened and the chip surface is crystallized. In the present invention, it is preferable that the chip whose surface is roughened as described above is dried at a temperature of 150 ° C. or more under reduced pressure.

The polyethylene naphthalate chip obtained as described above has excellent blocking resistance.

[0038]

The polyethylene naphthalate obtained by the production method according to the present invention does not stick to each other when supplied as chips as a raw material.
It can be supplied stably to molding machines.

According to the production method of the present invention, a polyethylene naphthalate which is less likely to be blocked when formed into chips can be obtained by the conventional pre-crystallization step, although it does not include the step of increasing the degree of crystallinity. For this reason,
When supplied as a molding material, air bubbles hardly enter, excellent supply stability, and good penetration. In addition, since the above-mentioned molding characteristics can be obtained without performing solid-phase polycondensation, it is also excellent in economic efficiency.

Hereinafter, the present invention will be described with reference to Examples.
The present invention is not limited to this embodiment.

[0041]

Example 1 15 kg of a polyethylene naphthalate resin having the following physical properties was obtained from 2,6-naphthalenedicarboxylic acid and ethylene glycol through an esterification step and a polycondensation reaction. The glass transition point (Tg) was 118 ° C., the melting point (Tm) was 267 ° C., and the temperature rise crystallization temperature (Tc) was 215 ° C.

The polyethylene naphthalate obtained as described above had an intrinsic viscosity [η] of 0.55 dl / g. Using this polyethylene naphthalate as a chip, 5 kg of the chip is poured into a Henschel type mixer (capacity 9).
Liters, manufactured by Mitsui Miike Works Co., Ltd .; Model FM10B)
And using a standard type blade, the number of rotations is 1480r
Shearing was performed by stirring at pm for 10 minutes. At this time, the chip had Ra'-Ra = 0.34 [mu] m. Ra =
It was 0.14 μm.

The treated chip was dried at 150 ° C. under vacuum to obtain a sample. Samples from Meiki Seisakusho Co., Ltd.
M-70B, a preform for a 1.5 liter carbonic acid bottle with a thickness of 5 mm
Molding was performed at 00 to 310 ° C., and the incidence of molded articles containing air bubbles in the preform was examined.

The preform is continuously formed, and a total of 30
Although zero preforms were produced, a total of four preforms containing air bubbles had an incidence of 1.3%.

[0045]

Comparative Example 1 A chip was obtained in the same manner as in Example 1 except that no shearing treatment was performed. The chips were dried under a vacuum of 150 ° C., and the number of preforms having bubbles in 300 pieces was determined. A total of 91 preforms in which bubbles were generated had an occurrence rate of 30%.

Claims (3)

(57) [Claims] 1. Polyethylene naphthalate is produced by polycondensation of a dicarboxylic acid containing 2,6-naphthalenedicarboxylic acid and a hydroxy compound containing ethylene glycol in a liquid phase to produce polyethylene naphthalate. A method for producing polyethylene naphthalate, comprising molding the obtained polyethylene naphthalate into chips, and subjecting the chips made of the polyethylene naphthalate to a shearing treatment to roughen the chip surface. 2. The method for producing polyethylene naphthalate according to claim 1, wherein the intrinsic viscosity [η] of the polyethylene naphthalate obtained by polycondensation is 0.30 to 0.80 dl / g. 3. 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 or more. The method for producing polyethylene naphthalate according to claim 1 or 2, wherein the chip surface is roughened so as to satisfy the following condition.