JP2011001459A - Manufacturing method and manufacturing apparatus for copolyester pellet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a copolyester pellet capable of manufacturing the pellet of the copolyester having a low glass transition temperature although it has crystallinity and also having a relatively low melting point with sufficient workability, and a manufacturing apparatus preferably used in the manufacturing method.SOLUTION: After a melt polymer comprising the copolyester comprising a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing 50 mol% or more of 1,6-hexane diol, containing 0.3-5.0 mass% of a crystal nucleating agent, and having a melting point (Tm) of 100-150°C is extruded in a strand 9 form, and is cooled and solidified, it is cut to manufacture the pellet 11. In this case, after the melt polymer is extruded into cooled water of a temperature of 30°C or lower in the strand 9 form and is cooled, it is cut and continuously subjected to heat treatment in hot water of 50-100°C for 1-60 seconds.

Description

  The present invention relates to a method and an apparatus for producing copolymer polyester pellets having a low melting point and excellent crystallinity.

  Synthetic fibers, especially polyester fibers such as polyethylene terephthalate, are indispensable as clothing and industrial materials due to their excellent dimensional stability, weather resistance, mechanical properties, durability, and recyclability. In many fields, polyester fibers are often used.

  In recent years, non-woven structures formed by adhering fibers have been proposed for automobile interior materials, and the non-woven structures may be bonded together for the purpose of reinforcing them. Thus, when non-woven structures are bonded to each other, both non-woven structures are obtained by interposing a non-woven structure made of a polymer having thermal adhesiveness between the non-woven structure and the non-woven structure, and applying heat treatment. Adhere. As the nonwoven fabric having such an adhesive property, a nonwoven fabric structure is mainly composed of a polyester fiber, and therefore, a nonwoven fabric composed of a polyester polymer is preferable from the viewpoint of recycling.

And as a copolymer polyester used for the fiber which forms the nonwoven fabric which has such adhesiveness, the amorphous polyester which copolymerized isophthalic acid is mainly used, for example.
However, the nonwoven fabric made of this amorphous copolymerized polyester fiber has a problem that the strength is lowered when it is kept at a high temperature, and the nonwoven fabric is deformed when a load is applied.

Patent Document 1 proposes a crystalline copolymerized polyester as a suitable copolymerized polyester for solving such problems and used for nonwoven fabrics used for applications requiring heat resistance.
However, since this copolyester has a low glass transition temperature, when it is extruded from a polycondensation can into strands after melt polymerization, and after cooling and cutting into pellets, if the strands are not sufficiently cooled, the cutter blade There is a problem in that it becomes impossible to cut by bonding to each other, or the pellets are fused after cutting and so-called continuous pellets are easily generated.
On the other hand, if the strand is cooled too much, the strand becomes too hard and cutting becomes difficult, powder is generated during cutting, and the pellet breaks.

As a solution to the above problem, Patent Document 2 describes a method for producing copolymer polyester pellets in which strand cooling conditions are adjusted according to the glass transition temperature of the copolymer polyester and then cut.
However, in this method, when the glass transition temperature of the copolyester is 20 ° C. or lower, even if it can be cut into pellets, the temperature inside the pellet is transmitted to the pellet surface in the subsequent process, and continuous pelletization by heat is promoted. In the worst case, there is a problem that it becomes a block-like lump.

  In addition, as described above, in the method described in Patent Document 2, the copolyester strand is cooled and cut to obtain pellets. The pelletizer used in this method does not have a heat treatment device, and the pellets after cooling are used. The heat treatment could not be performed.

Japanese Patent Laid-Open No. 9-12663 JP 11-138533 A

  The present invention solves the above-mentioned problems, and has a crystallinity, but has a low glass transition temperature and a relatively low melting point, and can produce copolyester pellets with good operability. It is an object of the present invention to provide a method and a manufacturing apparatus suitable for use in this manufacturing method.

As a result of intensive studies to solve the above problems, the present inventors have reached the present invention.
That is, the gist of the present invention is as follows.
(1) Consists of a dicarboxylic acid component containing terephthalic acid as a main component and a diol component of 1,6-hexanediol of 50 mol% or more, containing 0.3 to 5.0% by mass of a crystal nucleating agent, When a molten polymer composed of a copolyester having a Tm) of 100 to 150 ° C. is extruded into a strand, cooled and solidified, and then cut to produce pellets, the molten polymer is stranded in cooling water having a temperature of 30 ° C. or less. A method for producing copolyester pellets, characterized by being extruded, cooled and then continuously cut and heat-treated in warm water at 50 to 100 ° C. for 1 to 60 seconds.
(2) A pelletizer for cutting the strand discharged from the polycondensation can into pellets while cooling with cooling water and cooling, and a heat treatment apparatus for heat-treating the pellets cooled with the pelletizer with warm water. An apparatus for producing copolymer polyester pellets.

According to the method for producing a copolymerized polyester pellet of the present invention, a pellet of a copolymerized polyester having a low melting point and excellent crystallinity and having a high crystallization rate when the temperature is lowered cannot be cut by adhesion to a cutter blade. It can be stably obtained with good operability without causing problems such as fusion of pellets and generation of continuous pellets. And if the nonwoven fabric which formed this pellet into fibers is made to interpose when non-woven structures are made to adhere, it becomes possible to make the thermal bonding of non-woven structures low-temperature and high-speed.
Moreover, if the manufacturing apparatus of the copolyester pellet of this invention is used, it will become possible to manufacture stably the pellet which has said advantage.

Hereinafter, the present invention will be described in detail.
The copolyester used in the method for producing copolyester pellets of the present invention comprises a dicarboxylic acid component containing terephthalic acid as a main component and a diol component, and the diol component is 50 mol% or more of 1,6-hexanediol and other components. It consists of a diol component.

  The melting point (Tm) of the copolymerized polyester is 100 to 150 ° C, and preferably 110 to 140 ° C. When the Tm is less than 100 ° C., the thermal stability (heat resistance) when the nonwoven fabric obtained by fiberization is used in a high-temperature atmosphere is inferior. On the other hand, when it exceeds 150 ° C., it is necessary to increase the heat bonding processing temperature, which is inferior in workability and economy. Further, it is not preferable because the quality and texture of the product obtained by the heat treatment are impaired.

  The copolymerized polyester has terephthalic acid as a main component as a dicarboxylic acid component, and terephthalic acid (hereinafter referred to as TPA) is preferably 60 mol% or more, and more preferably 80 mol% or more. If the TPA is less than 60 mol%, the melting point of the polymer is not within the scope of the present invention, and the crystallinity tends to be lowered, which is not preferable.

  In addition, as a (copolymerization) acid component other than TPA, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, 1 as long as the effects of the present invention are not impaired. Unsaturated examples such as saturated aliphatic dicarboxylic acids exemplified by 1,3-cyclobutanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, dimer acid and the like, or ester-forming derivatives thereof, fumaric acid, maleic acid, itaconic acid and the like Fragrances exemplified by aliphatic dicarboxylic acids or their ester-forming derivatives, phthalic acid, isophthalic acid, 5- (alkali metal) sulfoisophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, etc. Group dicarboxylic acids or their ester-forming derivatives.

  Next, as a diol component of the copolymer polyester, 1,6-hexanediol (hereinafter referred to as HD) is 50 mol% or more, and as other components, ethylene glycol (hereinafter referred to as EG) or the like. It is preferable to use 1,4-butanediol (hereinafter referred to as BD). In the diol component, HD is 50 mol% or more, and preferably 60 to 95 mol%. When HD is less than 50 mol%, the melting point exceeds 150 ° C.

  When EG or BD is used together with HD as the diol component, EG or BD is preferably 5 to 50 mol%, more preferably 5 to 40 mol% in the diol component.

  Furthermore, the diol component includes other copolymer components other than HD, EG and BD, as long as the properties are not impaired, 1,2-propylene glycol, 1,3-propylene glycol, diethylene glycol, triethylene glycol, tetra For ethylene glycol, 1,4-butylene glycol, 1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, polyethylene glycol, polytrimethylene glycol, polytetramethylene glycol, etc. Exemplified aliphatic glycol, hydroquinone, 4,4′-dihydroxybisphenol, 1,4-bis (β-hydroxyethoxy) benzene, bisphenol A, 2,5-naphthalenediol, ethylene glycol is attached to these glycols Aromatic glycols exemplified in the glycol and the like can be used.

The above-mentioned copolymerized polyester has crystallinity in terms of composition, but by further containing a crystal nucleating agent, the crystallization rate during cooling can be improved.
The kind of the crystal nucleating agent is not particularly limited, but inorganic particles are preferable, and those containing silicon oxide such as talc or silica as the main component are effective. Other crystal nucleating agents include polyethylene wax and polyethylene glycol. The copolyester contains 0.3 to 5.0% by mass, preferably 0.5 to 4.0% by mass of the crystal nucleating agent as described above.

  The copolyester is further excellent in crystallinity by containing a crystal nucleating agent. When the content of the crystal nucleating agent is less than 0.3% by mass, the effect of improving the crystallinity of the polymer becomes insufficient. When the content exceeds 5.0% by mass, the content of the crystal nucleating agent is excessively increased. Not only inhibits the condensation reaction, but also deteriorates operability during spinning and drawing.

  In the copolyester, a stabilizer such as a phosphate ester compound or a hindered phenol compound, a cobalt compound, a fluorescent brightening agent, a color tone improving agent such as a dye, and the like, within a range not impairing the effects of the present invention. One type or two or more types of various additives such as matting agents such as titanium dioxide, plasticizers, pigments, antistatic agents, flame retardants, and dyeing agents may be added.

  In the present invention, it is necessary to extrude the molten polymer composed of the above-described copolymer polyester into a strand shape in cooling water and cut it into a pellet shape while cooling. The temperature of the cooling water used here needs to be 30 ° C. or lower, preferably 20 ° C. or lower, more preferably 15 ° C. or lower. When the temperature of the cooling water exceeds 30 ° C., the strands are not sufficiently cooled, and the strands adhere to the cutter blade and cannot be cut.

The pellets obtained above are continuously subjected to heat treatment with warm water, and then subjected to dehydration treatment as necessary to obtain target pellets. The temperature of the hot water used in the heat treatment is preferably 50 to 100 ° C, particularly 60 to 90 ° C. When the temperature of the hot water is less than 50 ° C., crystallization is insufficient and continuous pellets are generated.
Further, the heat treatment time with warm water needs to be 1 to 60 seconds, and preferably ~ seconds. When the heat treatment time is less than 1 second, there is no effect of the heat treatment, and when it exceeds 60 seconds, melting of the pellet surface gradually develops and tends to form continuous pellets.

  In the present invention, the size of the pellets to be obtained is not particularly limited, but the average particle size is preferably 0.5 mm or more, and considering the operability and the like in the subsequent process, about 0.6 to 8.0 mm Is particularly preferred. The measurement of the average particle diameter at this time is performed according to the dry screening test method described in JIS K0069.

  According to the present invention, copolymer polyester pellets can be stably obtained with good operability without causing problems such as inability to cut by adhesion to a cutter blade, fusion of pellets, generation of continuous pellets, and the like.

  Next, the manufacturing apparatus of the copolymer polyester pellet of this invention is demonstrated. The production apparatus of the present invention includes a pelletizer for cooling a strand discharged from a polycondensation can into pellets while cooling with cooling water, and a heat treatment apparatus for heat-treating the pellets cooled by the pelletizer with warm water. It comprises.

FIG. 1 is a schematic view showing an embodiment of the production apparatus of the present invention. In FIG. 1, 3 is a pelletizer and 12 is a heat treatment apparatus. The pelletizer 3 is provided with a cooling water containing valve 5 at the top and a cooling water return valve 6 at the bottom. Further, the heat treatment apparatus 12 is provided with a warm water containing valve 7 on the upstream side, a dehydrator 4 on the downstream side, and a hot water return valve 8 below the dehydrator 4. In the figure, 1 is a polycondensation can, 2 is a discharge valve, 9 is a strand, 10 is a pellet after cooling, and 11 is a pellet after heat treatment and dehydration.

  The molten polymer from the polycondensation can 1 is pressurized with an inert gas such as nitrogen gas, the discharge valve 2 is opened, and supplied to the pelletizer 3 in the state of a strand 9 through an optional nozzle or the like. Cooling water adjusted to a predetermined temperature is supplied to the pelletizer 3 from the cooling water containing valve 5, and is cut into a predetermined length by a rotary blade or the like to become a pellet 10. The supplied cooling water is discharged from the pelletizer 3 via the cooling water return valve 6.

  Next, the pellet 10 is supplied to the heat treatment apparatus 12. The heat treatment device 12 is supplied with warm water having a predetermined temperature from the warm water containing valve 7 and is discharged from the warm water return valve 8. The heat treatment time in the heat treatment apparatus 12 can be arbitrarily controlled by the opening degree of the hot water containing valve 7 or the supply pressure. The pellets 11 that have been subjected to the heat treatment with warm water and the dehydration process with the dehydrator 4 are delivered to the next process.

  If the production apparatus for copolymerized polyester pellets of the present invention is used, the copolymerized polyester pellets have good operability without causing problems such as inability to cut by adhesion to the cutter blade, fusion of pellets, generation of continuous pellets, etc. It is possible to easily carry out the production method of the present invention that can be obtained stably.

EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these. In the examples, measurement and evaluation of various characteristic values and the like were performed by the following methods.
(1) Intrinsic viscosity [η]
Measurement was performed under the conditions of a sample concentration of 0.5 mass% and a temperature of 20 ° C. using a mixture of equal mass of phenol and ethane tetrachloride as a solvent.
(2) Melting point Using a differential scanning calorimeter (Diamond DSC) manufactured by PerkinElmer Co., in a nitrogen stream at a temperature range of −20 ° C. to 250 ° C. and a temperature increase (temperature decrease) rate of 20 ° C./min. .
(3) Operability of cutter The following two stages were evaluated by the operability when pellets were continuously pelletized for a time, that is, the number of automatic stops due to an increase in the current value of the cutter.
(Circle): The number of times of an automatic stop is 0 times, x: The number of times of an automatic stop is 1 time or more, or the cutting | disconnection defect by fusion | bonding (4) The presence or absence of a continuous pellet The presence or absence of the continuous pellet was judged visually.

Example 1
The slurry of TPA and EG is continuously supplied to the esterification reactor and reacted under the conditions of a temperature of 250 ° C. and a pressure of 0.2 MPa, and a residence time of 8 hours is obtained to obtain a reaction product with an esterification reaction rate of 95%. It was. This reaction product was transferred to a polycondensation reaction vessel, HD was charged into the polycondensation reaction vessel, and stirred at a temperature of 240 ° C. and normal pressure for 1 hour. Next, an EG slurry containing tetrabutyl titanate as a polycondensation catalyst and talc having an average particle size of 1.0 μm and a specific surface area of 35 m ² / g as a crystal nucleating agent is put into the polycondensation can 1 and then the pressure in the can The polycondensation reaction is carried out for about 3 hours with stirring, and is composed of TPA as an acid component having an intrinsic viscosity of 0.95 and a melting point of 128 ° C., 15 mol% of EG as a glycol component, and 85 mol% of HD, and 0 as a nucleating agent. A copolyester containing 5% by mass of talc was obtained.

  Next, the polycondensation can 1 was pressurized to 0.8 MPa with nitrogen gas, extruded through a discharge valve 2 from a nozzle having 20 discharge holes with a diameter of 4 mm, and in the state of a strand 9, a pelletizer 3 (USG-manufactured by Automatic Co., Ltd.). 300), cooling water having a temperature of 4 ° C. is supplied from the cooling water valve 5 and the strand 9 is cooled to a predetermined length while being cut into pellets 10. Hot water (hot water) at a temperature of 82 ° C. was supplied from 7 and heat-treated under the condition of a heat treatment time of 5 seconds, and then the moisture on the pellet surface was dehydrated by the dehydrator 4 to obtain pellets 11 after the heat treatment and dehydration. .

Examples 2-3 and Comparative Examples 1-3
Pellets were obtained in the same manner as in Example 1 except that the pelletizing conditions were changed as shown in Table 1.

Example 4
Copolymer polyester consisting of 100 mol% TPA as acid component, 20 mol% BD as glycol component and 80 mol% HD and containing 0.5% by mass of talc as crystal nucleating agent (extreme viscosity 0.98, melting point 130 ° C) is used. Except that, pellets were obtained in the same manner as in Example 1.

Examples 5-6, Comparative Examples 4-6
Pellets were obtained in the same manner as in Example 1 except that the pelletizing conditions were changed as shown in Table 1.

  Table 1 shows the characteristic values, pelletization conditions, and evaluation results of the copolyesters in Examples 1 to 6 and Comparative Examples 1 to 6.

As apparent from Table 1, in Examples 1 to 6, copolymer polyester pellets could be obtained with good operability, and no continuous pellets were generated.
On the other hand, in Comparative Examples 1 and 4, since the temperature of the cooling water was high, the operability was poor and continuous pellets were also generated. Moreover, since the comparative examples 2 and 5 did not implement heat processing, operativity was bad and there were many continuous pellets. Next, in Comparative Examples 3 and 6, since the heat treatment time was long, the pellets were fused during the heat treatment and could not be discharged from the apparatus.

It is the schematic which shows one embodiment of the manufacturing apparatus of the copolyester pellet of this invention.

DESCRIPTION OF SYMBOLS 1 Polycondensation can 2 Discharge valve 3 Pelletizer 4 Dehydrator 5 Cooling water containing valve 6 Cooling water return valve 7 Hot water containing valve 8 Hot water return valve 9 Strand
10 pellets
11 Pellets after heat treatment and dehydration
12 Heat treatment equipment

Claims (2)

  It consists of a dicarboxylic acid component mainly composed of terephthalic acid and a diol component of 1,6-hexanediol of 50 mol% or more, contains 0.3 to 5.0% by mass of a crystal nucleating agent, and has a melting point (Tm). When a molten polymer composed of a copolyester at 100 to 150 ° C. is extruded into a strand shape, cooled and solidified, and then cut to produce pellets, the molten polymer is extruded into a cooling water at a temperature of 30 ° C. or less in a strand shape, A method for producing copolymerized polyester pellets, which is cut after cooling and continuously heat-treated in warm water at 50 to 100 ° C. for 1 to 60 seconds. It comprises a pelletizer for cutting a strand discharged from a polycondensation can into pellets while cooling with cooling water and cooling, and a heat treatment device for heat-treating the pellets cooled by the pelletizer with warm water. Equipment for producing copolyester pellets.