JP3957138B2 - Post-treatment method of polyester resin - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a post-treatment method for a polyester resin, and more particularly, a polyester resin that has been subjected to hot water contact treatment for deactivation of a polycondensation catalyst, and has a stable moldability, and particularly an injection blow bottle. It is related with the post-processing method of the polyester resin which can obtain the polyester resin useful for shaping | molding.
[0002]
[Prior art]
Conventionally, polyester resins such as polyethylene terephthalate resins are excellent in mechanical strength, chemical stability, transparency, gas barrier properties, safety and hygiene, etc., and are relatively inexpensive and lightweight. These bottles are usually used in injection molding of a bottomed tubular preform, and the preform is reheated and softened before being blown in a blow mold. Manufactured by stretch blow molding.
[0003]
These bottles for foods and drinks mainly use polyethylene terephthalate resin produced by melt polycondensation and solid phase polycondensation in the presence of a polycondensation catalyst such as a general-purpose antimony compound or germanium compound. At the time of melt molding such as injection molding of a preform, a by-product such as a cyclic trimer is generated in the resin, and the cyclic trimer contaminates the blow mold, and the mold There were problems such as greatly reducing productivity for cleaning. In contrast, a method of deactivating the catalyst in the resin by subjecting the resin after solid-phase polycondensation to hot water contact treatment with hot water to reduce the generation of by-products during the melt molding. (For example, see Japanese Patent Publication Nos. 7-14997, 7-37515, etc.) have been proposed and confirmed to be effective in preventing mold contamination.
[0004]
On the other hand, polyester resins typified by polyethylene terephthalate resin usually suffer from drawbacks such as a decrease in molecular weight due to hydrolysis in the molten state and a decrease in physical properties such as mechanical strength as a molded article. The produced resin is dried under heating, and further stored in an air or inert gas atmosphere having a low dew point, and is also dried under heating during molding. However, according to the study by the present inventors, in the polyester resin subjected to the hot water contact treatment, the moisture content at the time of packaging after cooling is the same as that in the case of drying under heating after the treatment. There is a problem that it shows a higher value than the resin that has not been applied, it is difficult to continuously obtain a stable low moisture content polyester resin, it is difficult to maintain the moldability of bottles and the like in a stable state It has been found.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above-mentioned present situation. Therefore, the present invention is a polyester resin subjected to a hot water contact treatment for deactivation of a polycondensation catalyst, and maintains a low water content. Therefore, an object of the present invention is to provide a post-treatment method for a polyester resin, which can obtain a polyester resin having stable moldability and particularly useful for molding an injection blow bottle or the like.
[0006]
[Means for Solving the Problems]
The present invention has found that after the hydrothermal contact treatment, drying under heating, and then the humidity of the atmosphere when cooling the resin affects the moisture content of the resin finally obtained. Accordingly, the present invention provides a polyester resin produced by melt polycondensation and solid-phase polycondensation in the presence of a polycondensation catalyst, with hot water and ethylene terephthalate units as the main structural repeating unit. After contacting and deactivating the polycondensation catalyst, drying is performed under heating, and then the gas temperature is 0.010 kg water / kg gas, and the absolute humidity is below, until the resin temperature is at least 60 ° C. The gist is a post-treatment method of a polyester resin which is subjected to a post-treatment to be cooled below.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The polyester resin in the post-treatment method of the polyester resin of the present invention is obtained by esterifying a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of ethylene glycol, and then in the presence of a polycondensation catalyst. Produced by melt polycondensation and solid phase polycondensation, and a polyester resin having an ethylene terephthalate unit as a main constituent repeating unit, wherein the proportion of terephthalic acid in the dicarboxylic acid component is 80 mol% or more, The proportion of the diol component is 80 mol% or more, and the ethylene terephthalate unit preferably occupies 64 mol% or more of the structural repeating unit. The proportion of terephthalic acid to the dicarboxylic acid component is 95 mol% or more, and the diol component of ethylene glycol Is a ratio of 95 mol% or more, Chi terephthalate units that account for at least 90 mol% of the structure repeating unit further preferred. When the ethylene terephthalate unit is less than the above range, the mechanical properties and heat resistance as a molded article are inferior.
[0008]
Examples of dicarboxylic acid components other than terephthalic acid include phthalic acid, isophthalic acid, phenylenedioxydicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, and 4,4′-diphenylketone. Dicarboxylic acids, aromatic dicarboxylic acids such as 4,4′-diphenoxyethanedicarboxylic acid, 4,4′-diphenylsulfone dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and fats such as hexahydroterephthalic acid and hexahydroisophthalic acid One or more of cyclic dicarboxylic acids and aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecadicarboxylic acid, dodecadicarboxylic acid, etc. However, it may be used as a copolymerization component.
[0009]
As glycol components other than ethylene glycol, for example, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene glycol, neopentyl glycol, diethylene glycol, polyethylene glycol, polytetramethylene ether glycol Aliphatic diols such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, alicyclic diols such as 1,4-cyclohexanedimethylol, and xylylene glycol, 4′-dihydroxybiphenyl, 2,2-bis (4′-hydroxyphenyl) propane, 2,2-bis (4′-β-hydroxyethoxyphenyl) propane, bis ( - hydroxyphenyl) sulfone, bis (4-beta-hydroxyethoxyphenyl) aromatic diol such as a sulfonic acid, one or two or more like may also be used as a copolymerization component.
[0010]
Furthermore, for example, hydroxycarboxylic acids and alkoxycarboxylic acids such as glycolic acid, p-hydroxybenzoic acid, p-β-hydroxyethoxybenzoic acid, and stearyl alcohol, benzyl alcohol, stearic acid, benzoic acid, t-butylbenzoic acid Monofunctional components such as benzoylbenzoic acid, trifunctional or more polyfunctional components such as tricarbaric acid, trimellitic acid, trimesic acid, pyromellitic acid, gallic acid, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, 1 type, or 2 or more types, etc. may be used as a copolymerization component.
[0011]
The production of the polyester resin in the present invention is basically based on a conventional production method of a polyester resin. That is, terephthalic acid and ethylene glycol, together with the above-mentioned copolymerization component used as needed, are put into a slurry preparation tank and mixed under stirring to form a raw material slurry. Under normal pressure to increased pressure in an esterification reaction tank After the esterification reaction under heating, the resulting polyester low molecular weight product as the esterification reaction product is transferred to a polycondensation tank, and the pressure is gradually reduced from normal pressure in the presence of a polycondensation catalyst. Then, melt polycondensation is carried out under heating, and subsequently, it is transferred to a solid phase polycondensation apparatus and subjected to solid phase polycondensation under heating. In addition, these are made by a continuous type or a batch type, and an esterification reaction tank, a polycondensation tank, and a solid-phase polycondensation apparatus may each be made into one stage or multistage.
[0012]
Here, preparation of the raw material slurry is usually performed by using terephthalic acid and ethylene glycol together with the above-described copolymer component used as necessary, and the molar ratio of the diol component to the dicarboxylic acid component, preferably 1.0 to 3. 0, more preferably in the range of 1.2 to 2.0, usually by mixing uniformly at a temperature of normal temperature to 100 ° C, preferably 30 to 80 ° C.
[0013]
The esterification reaction is carried out at a temperature of usually 150 to 280 ° C., preferably 180 to 270 ° C., more preferably 220 to 265 ° C. under a cage pressure of usually 0.11 MPa or less, preferably 0.06 MPa or less. In addition, the melt polycondensation is carried out at an absolute pressure of usually 10 to 0.01 kPa, preferably 5 to 0.05 kPa under a reduced pressure, usually 210 to 300 ° C., preferably 250 to 290 ° C. .
[0014]
Examples of polycondensation catalysts include germanium compounds such as germanium dioxide, germanium tetroxide, germanium hydroxide, germanium oxalate, germanium tetraethoxide, germanium tetra-n-butoxide, antimony trioxide, antimony acetate, and methoxyantimony. Antimony compounds, tetra-n-propyl titanate, tetra-i-propyl titanate, tetra-n-butyl titanate, titanium compounds such as titanium oxalate and titanium potassium oxalate are used. In the present invention, germanium compounds are used. Or / and a polyester resin using a titanium compound as a polycondensation catalyst is preferable.
[0015]
During polycondensation, together with the polycondensation catalyst, phosphoric compounds such as orthophosphoric acid, tris (triethylene glycol) phosphate, ethyl diethyl phosphonoacetate, ethyl acid phosphate, triethylene glycol acid phosphate, phosphorous acid coexist as stabilizers. It is preferable to do so.
[0016]
The addition of these polycondensation catalyst and stabilizer to the reaction system may be any stage of the slurry preparation process, the esterification reaction process, or the initial stage of the melt polycondensation process, The stabilizer is preferably added to the slurry preparation tank, and the polycondensation catalyst is transferred to the esterification reaction tank (the final reaction tank in the case of multiple stages) or the esterification reaction product to the polycondensation tank. It is preferable to add to the piping etc.
[0017]
In addition, the resin after melt polycondensation is usually extracted in the form of a strand from an extraction port provided at the bottom of the polycondensation tank, and is cooled with water or cooled with water and then cut with a cutter to form pellets, chips, etc. Prior to solid-phase polycondensation, the granules after melt polycondensation are dried, or in an inert gas atmosphere such as nitrogen, carbon dioxide, argon, etc., in a steam atmosphere, or in steam It is preferable to crystallize the resin granule surface by heating at a temperature of usually 120 to 200 ° C., preferably 130 to 180 ° C. in an inert gas atmosphere.
[0018]
The solid phase polycondensation is usually carried out at a temperature of 190 to 230 ° C., preferably 195 to 225 ° C. under an atmosphere of an inert gas such as nitrogen, carbon dioxide, and argon and under atmospheric pressure. By this solid phase polycondensation, the degree of polymerization of the resin can be further increased, and reaction by-products such as cyclic trimers can be reduced.
[0019]
In the polyester resin post-treatment method of the present invention, the polyester resin granules produced as described above are brought into contact with hot water to deactivate the polycondensation catalyst, and then dried under heating. In addition, it is essential to perform a post-treatment for cooling in a gas atmosphere of 0.010 kg water / kg gas and the following absolute humidity until the resin temperature reaches at least 60 ° C. or less.
[0020]
Here, the contact treatment of the polyester resin granular material with hot water is performed by, for example, supplying the resin granular material to a processing apparatus such as a silo type or a rotating cylindrical type and supplying hot water. In order to improve the contact efficiency by rotating the hopper, the resin particles are continuously fed into the hopper type processing equipment from the top, and hot water is continuously supplied in a cocurrent or countercurrent flow. The hot water temperature is usually 70 to 110 ° C., preferably 80 to 100 ° C., usually 3 minutes to 6 hours, preferably 5 minutes to 3 hours. Do it in time. This deactivates the polycondensation catalyst remaining in the resin.
[0021]
The polyester resin granules after the hot water contact treatment are drained by a draining device such as a vibrating screen or a Simon cutter, and then transferred to a drying device such as a hopper type, for example. Then, it is dried by ventilating a dry gas from the bottom. At that time, the dry gas may be atmospheric air, but is preferably dehumidified air or dry nitrogen, preferably 90 to 160 ° C., more preferably 100 to 150 ° C., particularly preferably 110 to 140 ° C. The resin granule is dried until the water content is preferably 0.05% by weight or less, more preferably 0.03% by weight or less.
[0022]
In the present invention, the humidity of the atmosphere at the time of cooling after drying is important, and the period until the resin temperature is at least 60 ° C. or less is 0.010 kg water / kg gas, in a gas atmosphere having the following absolute humidity: It is essential to cool, and it is preferable to be at least 50 ° C. or less, and more preferable to be at least 40 ° C. or less. Further, it is preferable to cool in the gas atmosphere of 0.007 kg water / kg gas and the following absolute humidity until the temperature becomes lower than those temperatures, 0.005 kg water / kg gas and the gas atmosphere of the following absolute humidity More preferred is cooling below. When the resin temperature exceeds the above range and the absolute humidity of the gas atmosphere exceeds the above range, it becomes difficult to maintain the post-treatment resin granules at a low water content.
[0023]
This cooling is performed, for example, by using a hopper type device and cooling the resin granular material introduced from the upper part by a cooling gas supplied from the lower part, using a fluidized bed type device, while maintaining the resin granular material in a fluid state. Cooling with a cooling gas supplied from the lower part of the pipe, or a cooling method in which the resin granular material is cooled by pneumatic transport in the pipe by a cooling gas, etc. can be performed. Although active gas may be used, it is preferable to use air from an economical viewpoint. The temperature of the cooling gas is preferably 35 ° C. or less, and more preferably 25 ° C. or less.
[0024]
When air is used as the cooling gas, if the ambient temperature and humidity are low, the absolute humidity condition as the cooling gas may be satisfied, but dehumidification is usually performed to satisfy the absolute humidity condition. As a dehumidifying method, for example, a method of adsorbing and removing moisture in the air using an adsorbent such as molecular sieve, or a method of dehumidifying by compressing and cooling atmospheric air to condense moisture A known method such as the above is adopted.
[0025]
The water content of the resin obtained by the post-treatment method of the polyester resin of the present invention is preferably 0.15% by weight or less, more preferably 0.10% by weight or less, and particularly preferably 0.07% by weight or less. it can.
[0026]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded.
[0027]
Example 1
Using a continuous polymerization apparatus comprising a slurry preparation tank, a two-stage esterification reaction tank connected in series therewith, and a three-stage polycondensation tank connected in series to the second esterification reaction tank, slurry preparation While continuously supplying 1,000 parts by weight of high-purity terephthalic acid and 564 parts by weight of ethylene glycol to the tank, a slurry is prepared by continuously adding and stirring and mixing orthophosphoric acid as a stabilizer, This slurry was continuously transferred to the first stage esterification reaction tank and then to the second stage esterification reaction tank. At that time, the temperature was 260 to 265 ° C. and the cage pressure was 0.005 to 0.043 MPa. In the second stage, germanium dioxide was continuously added as a polycondensation catalyst. Subsequently, the obtained esterification reaction product was continuously transferred to the first stage polycondensation tank, then to the second stage polycondensation tank, and further to the third stage polycondensation tank, Melt polycondensation is performed at a temperature of 273.5 to 278.5 ° C. and a reduced pressure of 2.81 to 0.22 kPa in absolute pressure, and is formed into a strand shape from an outlet provided at the bottom of the third stage polycondensation tank. The chip-shaped polyester resin was manufactured by extracting and cutting with a cutter after water-cooling.
[0028]
The obtained resin has an intrinsic viscosity of 0.58 dl / g measured by the method shown below, and the germanium compound content as a germanium atom and the phosphorus atom of the phosphorus compound measured by the method shown below. The content of was 61 ppm and 30 ppm, respectively.
[0029]
<Intrinsic viscosity>
The resin sample was dissolved in a mixed solvent of phenol / tetrachloroethane (weight ratio 1/1) and measured at 30 ° C. using an Ubbelohde viscometer.
<Germanium atom, phosphorus atom content>
A resin sample was ashed with hydrogen peroxide in the presence of sulfuric acid in a conventional manner, completely decomposed, and then fixed in distilled water, and then quantified by plasma emission spectrometry.
[0030]
Next, the obtained polyester resin chips are continuously supplied into a stirring crystallization machine maintained at 160 ° C. in a nitrogen atmosphere to be pre-crystallized, and then dried, followed by tower-type solid phase polycondensation. It was continuously supplied to the apparatus and subjected to solid phase polycondensation by heating at 206 ° C. under normal pressure for 18 hours under a nitrogen atmosphere. The intrinsic viscosity of the obtained resin was 0.74 dl / g.
[0031]
Subsequently, the obtained solid phase polycondensation polyester resin chip is continuously transferred to a hopper type hot water contact treatment device, and the resin chip is supplied from the upper part, and hot water at 93 ° C. is continuously supplied from the lower part. The polycondensation catalyst in the resin is deactivated by contacting with hot water at a residence time of 2.5 hours, drained with a screen-type dehydrator, and then put into a hopper-type drying device. It was continuously transferred, and resin chips were supplied from the upper part, and air at 140 ° C. was continuously supplied from the lower part in an amount of 2,600 Nm ³ / hour, and the residence time was 1.4 hours and dried. . At that time, when the moisture content of the resin chips sampled at the inlet and outlet of the drying apparatus was measured by the following method, they were 0.85 wt% and 0.02 wt%, respectively.
[0032]
<Moisture content>
An aluminum cup for weighing with an inner diameter of 80 mm and a height of 25 mm was dried at 140 ° C. for 2 hours with a hot air type electric constant temperature dryer (“DSF-11S type” manufactured by Isuzu Seisakusho), and left in a silica gel desiccator for 1 hour. Then, weigh [A (g)], then put about 20 g of resin sample into the aluminum cup, weigh [B (g)], and then dry it at 140 ° C. for 2 hours in the same dryer, inside the silica gel desiccator And then weighed [C (g)]. From these weighing results, the water content in the resin was calculated by the following formula.
Water content (%) = [(BC) / (BA)] × 100
[0033]
Subsequently, the dried resin chip is continuously transferred to a fluidized bed type cooling device, and air with an absolute humidity of 0.0042 kg water / kg air is blown as a cooling gas from the lower part while keeping the resin chip in a fluid state. As a result, the temperature of the resin chip was cooled to 45 ° C. The water content of the obtained resin chip was 0.06% by weight.
[0034]
Example 2
The post-treatment was performed in the same manner as in Example 1 except that air having an absolute humidity of 0.0093 kg water / kg air was used as the cooling gas. The water content of the obtained resin chip was 0.09% by weight.
[0035]
Comparative Example 1
Post-treatment was performed in the same manner as in Example 1 except that air having an absolute humidity of 0.0191 kg water / kg air was used as the cooling gas. The water content of the obtained resin chip was 0.17% by weight.
[0036]
Comparative Example 2
Resin chips after solid-phase polycondensation are not immediately subjected to hot water contact treatment and drying treatment, but are immediately introduced into a fluidized bed type cooling device, and air of absolute humidity 0.0214 kg water / kg air is used as a cooling gas. The post-treatment was performed in the same manner as in Example 1 except that was used. The moisture content of the resin chip at the inlet of the cooling device was 0.01% by weight, and the moisture content at the outlet of the cooling device was 0.03% by weight.
[0037]
【The invention's effect】
According to the present invention, a polyester resin that has been subjected to a hydrothermal contact treatment for deactivation of a polycondensation catalyst, can maintain a low water content, and thus has a stable moldability, particularly injection. A polyester resin post-treatment method capable of obtaining a polyester resin useful for molding a blow bottle or the like can be provided.

Claims (3)

The polyester resin produced by melt polycondensation and solid phase polycondensation in the presence of a polycondensation catalyst with an ethylene terephthalate unit as the main constituent repeating unit was brought into contact with hot water to deactivate the polycondensation catalyst. Then, it is dried under heating, and then subjected to a post-treatment for cooling in a gas atmosphere of 0.010 kg water / kg gas, absolute humidity below until the resin temperature reaches at least 60 ° C. To post-treat the polyester resin. The post-treatment method for a polyester resin according to claim 1, wherein the heating temperature during drying is 90 to 160 ° C. The post-treatment method for a polyester resin according to claim 1 or 2, wherein the gas to be cooled is air.