JP4657486B2 - Continuous crystallization method for crystalline resin pellet molding - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a crystallization technique of a raw material for molding processing in which a crystalline resin is melted, formed into a strand, and then pelletized, and the strand is maintained in an optimal slow cooling state to continuously crystallize and produce high quality pellets. It relates to the technology of manufacturing.
[0002]
[Prior art]
One of the crystallization technologies for forming raw materials using crystalline resins is to apply a stretching external force to the molten resin by extrusion to change it into a string-like strand shape. There is a conventional technique that advances the process and subsequently processes into pellets. An example is shown in FIG. As shown in FIG. 2A, the molten resin in the melting apparatus 1 is pressurized at a high pressure, and is processed into a strand by a die 1a so as to be extruded and run between the moving wheels 3 arranged on the right side in the drawing. In this traveling process, a crystallization operation is performed by gradually cooling from the outer periphery to the inside by a blowing operation from one place of room temperature air or gas for slow cooling not described here. During this operation, as indicated by a solid line in FIG. 5B, an appropriate tensile force generated by the rotational speed of the moving wheel acts as a stretching force on the strand c to increase the molecular orientation, and FIG. As shown by the solid line, the crystallization from the molten state to the crystalline state is completed according to the crystallization rate of the molten resin. Like homopolymers of molecular structure comprising a polymer resin and one kind of structural units of the perfect crystal structure consisting of the crystallization rate of 100% Ru crystallized resin der to hold the optimal condition of the crystallization.
[0003]
[Problems to be solved by the invention]
In the case of easy crystallization illustrated in FIG. 4, the extrusion pressure, the conveying speed, and the gas blowing from one place are the operation elements. However, these three elements alone are different from other types of crystalline resins. The same good results were not obtained. For example, if the conveying speed of the strand is appropriately increased, the stretching force and the stretching speed are increased, and a crystallized product with good crystallinity can be obtained. However, if some stickiness is not left in the moving wheel 3 portion, the frictional force at the time of winding is reduced, slippage occurs between the strand and the driving wheel, the running speed of the strand is lowered, and the operation is not stable. Similarly, if the progress of crystallization is too fast, deviating from the narrow range of proper operation, the stretching force is too large for the strand that is upstream of the portion where crystallization has progressed and that still contains a lot of molten state. FIG. 4B shows a fracture (1), and the crystallization state ends as shown in FIG. 4C (1). On the other hand, if the strand conveying speed is operated too slowly, the drawing force is insufficient and the uncrystallized (2) state continues as shown in FIG. 5B, and the molecular as shown in FIG. Cannot be crystallized in order to return to the original state (Reference Material (1): Yukichi Kure et al. “Polymer Crystallization by Flow” p27. 2nd line-p28.2 line, s55.6. Meeting).
Crystallization proceeds by an extended chain crystal generated by high-pressure operation of the resin or by a thickening phenomenon generated by relatively slow heat treatment at a low temperature (reference material (2): Yasuhisa Wada “Polymer solid physical properties” p91. Line 10-line 4 below, and line 94.10-line 2 below, s46.1. Baifukan). Therefore, each part of the strand where crystallization is proceeding is different from the other part at a slight distance, because the degree of crystallization formation changes, and the optimum conditions are different from the slow cooling operation in the previous stage. It cannot be ruled out by the operation. In other words, it is impossible to properly realize a non-uniform temperature drop in each part of the strand necessary for crystallization by operating the entire section to be slowly cooled by one kind of slow cooling means while conveying the strand. Yes, the optimum slow cooling rate of the entire strand cannot be adjusted or controlled by the slow cooling operation performed from one place.
In general, an oligomer having a higher molecular weight than a homopolymer or a copolymer obtained by synthesizing a heterogeneous polymer and exhibiting a crystallinity of less than 100% contains an amorphous component in the structure. However, the crystallization operation is difficult, and a strand in which the crystallized milky whitening occurs appropriately cannot be obtained.
[0004]
Here, compared to homopolymers that are easily crystallized, copolymers that are difficult to crystallize by conventional methods have higher market distribution and more opportunities for regeneration. Furthermore, as the quality of products, pellets and rushes with high crystallinity that have sufficiently achieved the crystallization rate peculiar to crystalline resins have higher market value. On the other hand, a crystalline resin with insufficient achievement of the crystallization rate has a high residual ratio of retained viscosity, causing non-uniform cutting when the strand is formed into pellets and chips, and adhesion and agglomeration with adjacent pellets. Resulting in a decline in commercial value.
The present invention has been developed in view of the above-described problems, and melts and extrudes flakes and fluff-like resin raw materials, and in the process from strand molding to pelletization, the optimum operating elements that have been confirmed by trial are crystallized. In addition to this, in order to perform optimum crystallization by arranging slow cooling means in several stages as necessary, we provide continuous crystallization technology for pellet molding of crystalline resin to produce high value products It is intended to do.
[0005]
[Means for Solving the Problems]
In the continuous crystallization method for forming a crystalline resin pellet according to the present invention, the crystalline resin flakes are melted by removing moisture, the molten resin is pressurized, extruded from a die and received by a conveying means, and at the conveying end. For the strands to be pelletized, the rest is placed on a conveying means that can be aerated on the entire circumference, and the position where milky whitening is completed from the transparent color of the original strand to complete the slow cooling is the optimum at the end of conveyance. The operation is tried for each crystalline resin in advance, and by the trial, the strand transport speed, the crystallization operation section distance, and one or more sections along the transport section are selectively arranged, and the cooling control can be made individually. The crystallization state of the strand and the slow cooling rate are properly controlled while controlling the amount of heat dissipated in the strand through the amount of heat or power supplied to the hot air generating means, air blowing means or heating means. It is obtained by the.
[0007]
[Action]
The continuous crystallization method of the crystalline resin of the present invention configured as described above is the supply-side energy operation for determining the appropriate conditions obtained by trials corresponding to the crystallization state during the transport of the strands left in the aerated state. Since the slow cooling rate is controlled and adjusted so that the crystallization operation target can be changed for each different crystalline resin, the follow-up corresponding to the internal change of the resin structure accompanying the crystallization including the thickening phenomenon In addition to being able to perform the operation, the portion that loses excessively the tackiness generated on the outer surface of the strand can be selectively partially heated to restore an appropriate viscosity.
The apparatus for carrying out the method of the present invention comprises a mesh conveyor around which a strand is divided and supported and the front and back of which is circulated, and a conveyor belt is wound around. The heating means is a slow cooling means that is arranged via a control device, and by adjusting it, a crystallization device with a simple structure is used for homopolymers that are easily crystallized, or a delicate slow cooling operation for crystallization. In the required crystalline resin, a plurality of heating means and blowers arranged in a row along the conveying means are selectively provided and operated, so that an environment with a temperature drop suitable for the crystallization operation in the conveying process can be obtained. Therefore, a slow cooling environment corresponding to the slow cooling control of resins with different crystallization operations can be formed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the continuous crystallization method for pellet molding of crystalline resin and its apparatus according to the present invention will be described with reference to the drawings. Here, FIG. 1 explains the method of the present invention, (A) is a process diagram showing the present crystallization method, (B) is a schematic diagram showing a strand slow cooling means in (A), and FIG. In the same way, the slow cooling operation method is explained, (A) is a slow cooling curve diagram of the strand showing the optimum operating state of the slow cooling means in the crystallization process, and (B) is generated in the strand in the operating process of (A). FIG. 3 illustrates the apparatus of the present invention, (A) is a partial side view showing one embodiment thereof, (B) is a view taken along the line A-A 'in (A), (C) is a block diagram showing one embodiment of slow cooling means control.
[0009]
As shown in FIG. 1A, the method of the present invention is divided into four stages in FIG. 1A, by performing trial (test operation) of the optimal crystallization operation for crystallization in advance for the resin to be crystallized in 1). The operation value for determining the slow cooling speed peculiar to the resin, that is, the transport length of the slow cooling operation section, the transport speed of the transport means, the supply heat amount for determining the strand temperature in each section transported while appropriately lowering the temperature, etc. Select the optimum operating value.
In this operation, as shown in 2) of the same figure (A), the resin flake a is melted, the molten resin is pressurized to the resin b to be stretched, extruded, formed into a string-like strand c, and completely transferred. Proceeding with the operation of allowing the strand to stand in an aerated state, and then the strand c placed on the conveying means as shown in 3), the temperature range is from almost the glassy displacement point of the resin to be crystallized to room temperature, The position where the strand turns milky white from the vitreous material is set as the conveyance end while adjusting the slow cooling speed for performing the supply heat amount operation for cooling slowly by the air blowing means 5 or the heating means 6 in a plurality of stages. At the crystallization end position, the strand c shown in 4) is shredded and formed into pellets d.
As shown in FIG. 5B, the heating plate 6a for gradually cooling the temperature of the strand c or the hot air generating means 4 for supplying the conditioned air Am is directly heated or indirectly heated, or by a heating method using them in combination. The amount of heat supplied may be supplied. As a heat source, an electric system such as electric power, electron beam heating, or a laser, or an apparatus that can be effectively used under the thermal control management of the whole factory including exhaust heat may be used. In the drawing, one embodiment is shown by a solid line, another embodiment is shown by a broken line, an alternate long and short dash line shows an air passage or a ventilation space 7a, and a heating means shows a heating means 6 for supplying heat to the hot air generating means 4. Although not shown here, the types of heat supplied to the slow cooling means include heat above room temperature and cold heat below room temperature such as electronic cooling heat due to the Peltier effect and cooling heat generated in the factory (including exhaust heat). is there.
[0010]
As shown in FIG. 3 (A), an apparatus for carrying out the method according to the present invention is attached to the melting device 1 for melting and pressurizing the dewatered resin and its end, and continuously extruding the molten resin. A die 1a to be formed into a strand c, a crystallization device 8 that conveys the extruded strand while crystallization, and a pelletizer device 9 that shreds the crystallized strand c are provided. The crystallization device 8 includes a mesh conveyor 2 on which a melted strand c is placed at the initial end, an air passage case 7 that forms a ventilation space 7a around the conveyor and that can cool the entire periphery of the strand c, and the case The heating means 6 for gradually cooling the strands to which the temperature detecting sensor 5b and the heating plate temperature detecting sensor 6b attached to the mesh conveyor 2 are provided, and installed in the upper case in the wind path on the conveyance end side. The power supply circuit 10 and the control device 11 are arranged in the lower part of the mesh conveyor and stored in the main body case, and the heating means and the blower are linked so that the cooling of the strand c can be controlled. ing.
[0011]
【Example】
Examples of the continuous crystallization method for forming a crystalline resin pellet according to the present invention will be described. When the crystallization of the target resin to be crystallized is a trial, and the change in the crystallization state of the strands in the entire conveyance section is obtained as shown in FIG. 2B, the optimum slow cooling curve of the strand is shown in FIG. ) As shown. Accordingly, the slow cooling means 4, 5, 6 are distributed and arranged at, for example, four positions a to d shown in FIG. When the heating plate 6a is used as the slow cooling means, a blower is disposed at the slow cooling end position d and cooled at room temperature. When the hot air generating means 4 is used, the blown conditioned air Am is adjusted to be lower than the surface temperature T of the strand c, and the temperature of each blown air is individually adjusted. The blown-out position of the conditioned air divided into several stages is a to d with the end added. The slow cooling means for a specific homopolymer is not provided with a heating plate or conditioned air, but only one blower 5 that blows out normal temperature air, or several in a row, are arranged at a slow cooling position in the air passage 7a. The temperature of the strand c can be controlled.
[0012]
As Example 1 of the method of the present invention, a crystallization resin (Eastman Co., Ltd .: product number 9921) pulverized material copolymer, which takes time for crystallization, was melted and subjected to a crystallization operation. At trial, the extrusion molten resin amount is 120 L / Hr, the extrusion pressure is 250 kg / cm ² G, the resin temperature just before extrusion is 300 ° C., and the conveying speed of the strand c is 12 m / min. When the distance is 5 m, the strand surface temperature of about 3 cm below the heater in the first stage is 260 ° C., the conveying end temperature of the plate heater 6 a is 350 ° C., the conveyor belt belt surface temperature is 180 ° C. Optimum crystallization operation was obtained when the air blowing temperature was set to room temperature, the amount of air blown generated at the conveyance end 500 m <3> / Hr, the number of slow cooling compartments to be cascaded by the conveying means at this time, and the strand c diameter 4 mm were set. .
Similarly, as Example 2, homopolymeric crystallized resin (Eastman: product number 031A) pulverized material was tried in the same manner as described above, and all the slow cooling means were transferred from the plate heater 6a to the blower 5 that cooled at room temperature. When it was replaced and gradually cooled at 2000 m 3 / Hr and the other operating conditions were the same as in Example 1, the optimum crystallization operation was obtained. In order to prevent detachment from the belt due to a decrease in the stickiness of the strand, a spot heating electric heating means (not shown) is configured and arranged in the area adjacent to the conveyance end. In both of the above embodiments, the screen mesh of the belt used for the conveying means 2 is about 5 mm square, and the operation value for performing the slow cooling control of the temperature drop for each number of stages depends on the optimum operation temperature or the amount of supplied power obtained by trial. Operated. These controls are performed by using a computer system including I / O equipment, storage means, CPU, and controller not described here, and by appropriately arranging milky whitening position detection sensors along the conveyance path and performing automation by sequence or feedback control. You can do it.
[0013]
An embodiment of an apparatus for carrying out the method according to the invention will be described with reference to FIG. As shown in FIG. 6A, the molten resin is disposed on the left side from the die 1a according to the set pressure (about 200-250 kg / cm 2 G) indicated by the resin pressure detection sensor 1b from the melting device 1 on the right side of the figure. It is extruded toward 9 and formed into a strand c that is molded and placed in a crystallization apparatus 8 disposed in the middle of both apparatuses. The strand c is then conveyed out of the terminal of the crystallization apparatus. In the crystallization apparatus, a mesh conveyor 2 shown in FIG. 1B travels around, a strand c is placed on an endless perforated screen belt of the conveyor, and an opening diameter of the die 1a (about 3 mm). -4 mm) and the number of holes (about 20 or less), the amount of resin corresponding to the number of strands is conveyed. The strand conveying belt forms a ventilation space 7a by an air passage case 7 except for openings at both left and right ends in the figure. Heating means (plate heater or infrared heater) 6 is arranged in several stages in the upper row of the strand in the upper part of the ventilation space, and gradually cooled air is generated from the upper part of the ventilation space 7a adjacent to the lower side of the heating plate. A blower 5 is provided. A temperature detection sensor 5b is provided for each section of the ventilation space divided into the columns where the slow cooling means 5 and 6 are arranged, and each heating means 6 directly detects a heater plate temperature detection sensor 6b. Is attached.
[0014]
The blower and the heating plate are attached to and held in an airway case 7 of about 20 to 50 mm above the strand c, and are covered with a casing so that the devices can be inspected together with the airway case. ing. A main body case that supports the entire crystallization apparatus 8 including the mesh conveyor 2 is provided at the lower part of the casing, and the power supply circuit 10 and the control device 11 are stored in the main body case, and an operation panel is formed on the front panel to be stored. is doing. In addition, the arrow shown to the figure (B) is an inspection opening direction of a main body case.
As shown in FIG. 5C, the control device 11 receives signals from the airway temperature detection sensor 5b and the heating plate temperature detection sensor 6b, generates a control signal to the power supply circuit 10, and Each output management of the heating plate 6a is performed.
[0015]
The thus-configured continuous crystallization apparatus for crystalline resin pellet molding of the present invention operates as follows. The strand c, which is controlled by the resin pressure specified for each crystalline resin to be crystallized and is extruded from the melting apparatus 1, has a glassy transparent color, or about 30 from the melting point in a relatively large number of substances. When the temperature is said to drop, the molecular arrangement is adjusted by extruding in a known state instead of the transparent color (reference material (2): lines 67.4-6). The strand driven by the conveyor 2 is subjected to heat removal adjustment by direct radiation or convection heat from the heating plate 6 disposed above. At this time, since the strand c is in the entire aeration state, the slow cooling action is not biased, and each part of the strand placed on the conveyor 2 is strongly affected by the internal stress that changes in the adjacent front and rear parts. Absent. Therefore, the crystallization growth phenomenon occurring inside is generated almost individually in a narrow structural range, and the crystal arrangement is expanded. The strand c at the beginning of extrusion has adhesiveness on the outer surface wall surface and easily adheres to the mesh conveyor. However, the outer surface wall of the strand at a position where the milky whitening and crystallization are completed is caused by room temperature air in the conveyance termination area. A slow cooling operation is added to lose the adhesiveness, and the curability suitable for cutting is ensured to facilitate pellet forming cutting.
[0016]
【The invention's effect】
Of the present invention, according to the crystalline resin pellets for molding a continuous crystallization how, taken up in specific crystalline resin performed by forming into strands, supplying heat separately crystallization effect of progression to the internal structure in a plurality of stages Since it is a crystallization operation advanced by a control operation from the side, continuous crystallization of strands and formation of crystallization pellets can be achieved under the best conditions, and continuous operation can be stably continued. In addition, since the technology of the present invention establishes a highly reliable crystallization method for a copolymer that has been difficult to crystallize and is unstable, it is useful for a recycling method for recycling a polymer product widely distributed in society. The present invention significantly contributes to the general improvement of the crystallization technology that increases the product value of the processed product for forming raw materials.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 illustrates a continuous resin crystallization method for regenerating resin for molding pellets according to the present invention, wherein (A) is a process diagram showing the crystallization method, and (B) is a method for slowly cooling a strand in (A). It is a schematic diagram which shows.
FIGS. 2A and 2B are diagrams for explaining the method of slow cooling operation according to the present invention, in which FIG. 2A is a strand slow cooling curve diagram showing the optimum operating state of the slow cooling means in the crystallization process, and FIG. It is a crystallization change schematic diagram which generate | occur | produces in the strand of a process.
FIGS. 3A and 3B are diagrams for explaining a continuous resin crystallization apparatus for recycling pellet molding according to the present invention, in which FIG. 3A is a partial side view showing one embodiment thereof, and FIG. 3B is AA ′ of FIG. An arrow view and (C) are block diagrams which show one Example of slow cooling means control.
FIGS. 4A and 4B are diagrams for explaining a conventional technique related to continuous crystallization of a regenerating resin for pellet molding, in which FIG. 4A is a partial cross-sectional view showing a strand slow cooling operation, and FIG. 4B is an operation process of FIG. The state schematic diagram which shows the stress which generate | occur | produces in a strand, (C) is a crystallization change schematic diagram of the strand corresponding to (B).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Melting apparatus 1a Dies 1b Resin pressure detection sensor 2 Mesh conveyor 3 Driving wheel 4 Hot air generating means 5 Blower 5b Temperature detection sensor 6 in an air passage 6 Heating means 6a Heating plate (plate heater)
6b Heating plate temperature detection sensor 7 Air passage case 7a Air passage, ventilation space 8 Crystallizer 9 Pelletizer device 10 Power supply circuit 11 Controller a Flakes b Molten resin c Strand d Pellet (1) Strand in a state where breakage occurs (2) Strands that remain uncrystallized

Claims (1)

The crystalline resin flakes (a) are melted by removing moisture, the molten resin (b) is pressurized, extruded from the die (1a), received by the conveying means (2), and pelletized at the conveying end. The position where the entire end of the strand (c) is left on the conveying means that can be aerated and milky whitened from the transparent color of the original strand to complete the slow cooling is the optimum at the end of conveyance. The operation is tried for each crystalline resin in advance, and by the trial, it is selectively arranged in one or a plurality of sections along the transport speed of the strand (c), the crystallization operation section distance, and the transport section. While controlling the amount of heat dissipated in the strand (c) through the amount of heat or power supplied to the hot air generating means (4), the blowing means (5) or the heating means (6) capable of slow cooling, the strand crystals are controlled. The cooling state and slow cooling rate Continuous crystallization method for pelletization of the crystalline resin, characterized in that so as to positively operated.

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