JP2013001763A - Method and device of treating polymeric compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device of treating a polymeric compound producing a polymeric product having a mechanical property and a molecular weight each approximately equal to that of a virgin material without using a kneading disk in a screw piece of an extruder for reaction.SOLUTION: In the method for treating the polymeric compound producing the polymeric product by reacting the polymeric compound with a subcritical or supercritical fluid agent in the extruder 10 for reaction, the screw piece 12 rotating together with the screw shaft 11 of the extruder 10 for reaction has a structure which does not give shear to the polymeric compound and can endure high temperature and high pressure.

Description

  The present invention relates to a polymer compound processing method and apparatus for producing a polymer product by reacting a polymer compound and a subcritical or supercritical fluid drug in a reaction extruder.

  Polyethylene, which is a general-purpose polymer compound material, is a material with excellent electrical insulation, and is widely used as a coating material for electric wires and cables. In addition, a large amount of cross-linked polyethylene imparted with heat resistance by three-dimensionally cross-linking polyethylene molecules is used as a coating material for electric wires and cables.

  Usually, polyethylene is thermoplastic, so it can be molded again and is widely recycled. However, cross-linked polyethylene is not thermoplastic, so material recycling has not been promoted much, and most are landfilled and incinerated. Will be disposed of.

  With regard to such cross-linked polyethylene, there is a growing movement to carry out material recycling, and a technology that makes this possible is emerging. For example, Patent Document 1 discloses a method of thermoplasticizing by cutting a molecular chain of a crosslinked polyethylene using a shearing force of a screw in an extruder. A method is disclosed in which a siloxane bond, which is a cross-linked bond of a silane cross-linked polymer, is selectively cut and thermoplasticized by contact with a critical or supercritical alcohol or carbonate.

  In particular, in the method of thermoplasticizing using a subcritical or supercritical alcohol or carbonate ester, since the decrease in the polyethylene molecular weight is less than that of the method disclosed in Patent Document 1, the regeneration has relatively good mechanical properties. Polyethylene is obtained.

Japanese Patent No. 3026270 Japanese Patent No. 4081454 JP 2010-1385 A JP 2006-26949 A

  In particular, in the processing methods shown in Patent Document 1 and Patent Document 2, a (biaxial) extruder is used, and the screw configuration is used for the purpose of applying shear to the crosslinked polyethylene and filling the crosslinked polyethylene under high pressure. In many cases, a kneading disk (a kneading screw piece composed of an elliptical disk) is used in a part of or a wide area.

  For this reason, excessively shearing is applied to crosslinked polyethylene and recycled polyethylene treated with crosslinked polyethylene, whether intentionally or unintentionally, so that the degradation of mechanical properties and polyethylene molecular weight of recycled polyethylene is avoided compared to virgin materials. Absent.

  Accordingly, an object of the present invention is to provide a method for treating a polymer compound that generates a polymer product having mechanical properties and molecular weight substantially equal to that of a virgin material without using a kneading disk for the screw piece of the reaction extruder. And providing an apparatus.

  The present invention, which was created to achieve this object, is a method for treating a polymer compound in which a polymer compound and a subcritical or supercritical fluid drug are reacted in a reaction extruder to produce a polymer product. In this method, the screw piece that rotates integrally with the screw shaft of the reaction extruder has a structure that can withstand high temperature and pressure without shearing the polymer compound.

  Further, the present invention provides a processing apparatus for a polymer compound that generates a polymer product by reacting a polymer compound and a subcritical or supercritical fluid drug in a reaction extruder. The polymer compound supply unit, the injection unit for injecting the drug, the seal unit for preventing the drug from flowing back to the supply unit side, and the mixture of the polymer compound and the drug extruder. A screw part that rotates integrally with the screw shaft of the reaction extruder, and a seal ring that is provided on the downstream side of the extruder with respect to the screw piece. Thus, the screw piece is a polymer compound processing apparatus having a structure capable of withstanding high temperature and high pressure without shearing the polymer compound.

  When the pressure of the polymer compound is applied to the seal portion, the surface of the screw piece approaches or comes into contact with the cylinder inner wall of the reaction extruder, supports the screw shaft, and vibrates or deforms the screw shaft. It is preferable that a protrusion-like support body having a curve to prevent the above is formed.

  The clearance between the apex of the support and the cylinder inner wall when the reaction extruder is stopped is preferably 0.5 mm or more and 1.5 mm or less.

  The screw piece may include at least one support body at L / D (screw shaft length (L) / screw shaft section diameter (D)) = 0.5 mm.

  The reaction extruder may be a twin screw extruder.

  According to the present invention, a polymer product having substantially the same mechanical properties and molecular weight as that of a virgin material can be produced without using a kneading disk for the screw piece of the reaction extruder.

It is a figure which shows an example of the screw piece used for the processing method of the high molecular compound which concerns on this invention, and its arrangement | positioning, (a) is sectional drawing, (b) is a side view. It is a schematic diagram of the seal | sticker part vicinity which shows the screw of the extruder for reaction. It is a figure which shows an example of the screw piece used for the processing method of the high molecular compound which concerns on this invention, and its arrangement | positioning, (a) is sectional drawing, (b) is a side view. It is a figure which shows an example of the screw piece used for the processing method of the high molecular compound which concerns on this invention, and its arrangement | positioning, (a) is sectional drawing, (b) is a side view. It is a figure which shows an example of the screw piece used for the processing method of the high molecular compound which concerns on this invention, and its arrangement | positioning, (a) is sectional drawing, (b) is a side view. It is a figure which shows an example of the screw piece used for the processing method of the high molecular compound which concerns on this invention, and its arrangement | positioning, (a) is sectional drawing, (b) is a side view. It is a figure which shows an example of the screw piece used for the processing method of the high molecular compound which concerns on this invention, and its arrangement | positioning, (a) is sectional drawing, (b) is a side view. It is a figure which shows an example of the screw piece used for the processing method of the high molecular compound which concerns on this invention, and its arrangement | positioning, (a) is sectional drawing, (b) is a side view. It is the schematic which shows the processing apparatus of the high molecular compound which concerns on one embodiment of this invention. 6 is a schematic view in the vicinity of a seal portion showing a screw of a reaction extruder used in Comparative Example 1. FIG. 6 is a schematic view of the vicinity of a seal portion showing a screw of a reaction extruder used in Comparative Example 2. FIG. 6 is a schematic view of the vicinity of a seal portion showing a screw of a reaction extruder used in Comparative Example 3. FIG. It is a figure which shows an example of the conventional screw piece and its arrangement | positioning, (a) is sectional drawing, (b) is a perspective view.

  The method for treating a polymer compound according to the present invention is a method for producing a polymer product by reacting a polymer compound and a subcritical or supercritical fluid drug in a reaction extruder. In order to produce a polymer product having mechanical properties and molecular weight almost equal to virgin material without using a kneading disk for the screw piece.

  Usually, a kneading disk is a screw piece that is used for kneading and dispersing polymer compounds and is also suitable for use under high pressure. The kneading disk may be applied to a seal part in a high-pressure environment that is filled with a high molecular compound particularly in the extruder shown in Patent Document 2, and as shown in Patent Document 4, a supercritical fluid is used. It may be used for the purpose of kneading and deaeration in a conventional extruder.

  Considering the mechanical properties of the polymer product, the shear applied by the kneading disk leads to a decrease in molecular weight, so it is desirable to reduce the use area as much as possible or not to use it.

  For example, in the conventional extruder shown in Patent Document 2, the seal portion is configured by combining a kneading disk and a seal ring (ring-shaped sealing piece having a high damming effect).

  In the case of using the extruder having the configuration shown in Patent Document 2, in order to suppress the shearing of the polymer product, when the configuration is such that the kneading disk is simply removed, the seal portion supplies the polymer compound. It is composed of a full flight (conveying screw piece with blades for feeding material) used for the part and a seal ring. When a sudden pressure rise occurs before the seal ring, the full flight is Thus, it is not intended for kneading, and therefore, it is more brittle than a kneading disk, and problems such as breakage of full flight blades are expected.

  Therefore, in order to suppress the shear while increasing the pressure stepwise, the torpedo piece is the most suitable screw piece for suppressing the shear applied to the polymer compound by increasing the filling rate of the polymer compound at the seal portion. (The cylindrical screw piece has a large space volume in the cylinder and is effective for extending the residence time). However, the distance (clearance) between the cylinder and the screw piece when the extruder is stopped is considered. Because it is relatively large, when used under high pressure, if the pressure of the polymer compound is not uniform, the screw shaft will vibrate and deform due to the stress caused by the pressure. In the worst case, the screw shaft may break or other screw Since the piece repeatedly contacts (galling) with the cylinder wall of the extruder, problems such as wear and breakage of the screw piece and damage to the cylinder may occur. It is difficult to apply to.

  Therefore, in such a part that is filled with such a polymer compound and becomes a high temperature and high pressure, particularly in the seal part of the reaction extruder, a piece having a structure that can withstand the high temperature and high pressure without shearing the polymer compound is disposed. This has led to the present invention.

  As one of such forms, a screw piece having a protruding support on the outer surface of the torpedo piece may be arranged instead of the kneading disk. The protrusion-like support has an effect of minimizing the vibration of the screw shaft when the screw piece is subjected to stress, so that the torpedo piece can be used under high pressure.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  As shown in FIGS. 1 and 2, the polymer compound processing method according to the present embodiment reacts a polymer compound with a subcritical or supercritical fluid chemical in a reaction extruder 10 to produce a polymer. The screw piece 12 that rotates integrally with the screw shaft 11 of the reaction extruder 10 has a structure that can withstand high temperature and high pressure without shearing the polymer compound. To do.

  The polymer compound processing apparatus used in this polymer compound processing method includes a reaction extruder 10, which includes a polymer compound supply unit 13 and an injection unit for injecting a drug. 14, a seal unit 15 for preventing the drug from flowing backward to the supply unit 13 side, and a transport unit 16 for transporting the mixture of the polymer compound and the drug to the downstream side of the extruder.

  The reaction extruder 10 may be a single-screw extruder or a twin-screw extruder, but is preferably a twin-screw extruder from the viewpoint of sealing properties. As shown in FIG. 2, in the case of a twin screw extruder, since a seal ring 17 described later is installed on each screw shaft 11 so as to be engaged with the seal portion 15, the sealing performance is high, and the filling rate of the polymer compound Can be increased efficiently.

  The seal portion 15 includes a screw piece portion having a screw piece 12 that rotates integrally with the screw shaft 11 of the reaction extruder 10, and a seal ring portion having a seal ring 17 provided on the downstream side of the extruder from the screw piece 12. It consists of. That is, the seal part 15 is provided with a plurality of screw pieces 12 and one seal ring 17 for each screw shaft.

  The screw piece 12 and the seal ring 17 are provided in front of the injection portion 14. Further, the screw piece 12 has a structure in which the polymer compound is not sheared and can withstand high temperature and high pressure. As a particularly effective method, the screw piece 12 has a structure in which a support 18 is provided on the surface of the screw piece 12.

  In the conventional processing method (decomposing method), a method is used in which the material is sheared at the seal portion 15 filled with the material to decompose the cross-linking of the material. Therefore, the seal portion 15 has been ground using a kneading disk.

  As shown in FIG. 13, the kneading disk has a structure in which the kneading disk 60 is installed perpendicular to the screw shaft 11, and therefore does not have a function of feeding material as in full flight. Since the approaching surface 61 is a square with a corner, the surface 61 stays in the part where the kneading disk is provided by the material sent out from the supply part composed of a piece having a function of feeding out the material such as full flight. Unless the material is extruded downstream of the extruder, this portion of the material is sheared by the face 61.

  Also in the present embodiment, since filling the polymer compound is not different from the conventional one, the support 18 is installed perpendicular to the screw shaft 11 and does not have a function of feeding out the material, and is fed from the supply unit 13. The polymer compound is pushed out by the polymer compound pressure, and the polymer compound is sequentially fed into the injection unit 14.

  However, in this embodiment, since the apparatus is not used to shear the polymer compound but to be used for the method of reactively decomposing the crosslinking with a drug, it is not desirable to shear the polymer compound at the seal portion 15.

  Therefore, the screw piece 12 provided in the seal portion 15 is provided with a support 18 that supports the screw shaft 11 in order to suppress vibration of the screw shaft 11. Since it is preferable not to apply the stress to the polymer compound by the support 18 or to suppress it to the minimum, the portion of the support 18 that approaches or contacts the cylinder inner wall 19 is as shown in FIG. , To be a point or a curved surface.

  The full flight 20 is provided in the conveyance part 16 containing the supply part 13 and the injection | pouring part 14 which are the objectives which send out a high molecular compound or a high molecular compound, a chemical | medical agent, and its reaction material. The full flight 20 has a function of feeding the material in the axial direction because the blades 21 are provided spirally along the screw shaft 11.

  On the other hand, the screw piece used for the seal part 15 for the purpose of preventing the back flow of the drug by filling the polymer compound does not need a function of conveying the polymer compound.

  Hereinafter, the structure of the screw piece will be described in detail.

  The polymer compound treatment method (decomposition method) according to the present invention is a method in which a polymer compound is not decomposed by shearing by the reaction extruder 10, but is reacted and decomposed by a chemical. Therefore, the kneading disk 60 is not used. Furthermore, since the high molecular compound is filled and stays and becomes high pressure, the seal portion 15 is required to be configured with a screw piece that can withstand it.

  Any screw piece that can withstand use under high temperature and high pressure without giving shear to the polymer compound can be used. As an example, a screw piece 12 having a curved support 18 formed thereon is provided. The method is effective. When the end has a rounded shape, wear is suppressed even when used under high pressure, and shear applied to the polymer compound can be reduced.

  For this reason, the surface of the screw piece 12 is brought close to or in contact with the cylinder inner wall 19 of the reaction extruder 10 when the pressure of the polymer compound is applied to the seal portion 15, and supports the screw shaft 11. A projecting support 18 having a curved shape that prevents vibration and deformation of the shaft 11 is formed.

  The shape of the support 18 is a curved line having no corners, and the portion in contact with the cylinder inner wall 19 is preferably a curved surface having no points or corners. In consideration of stability, it is preferable that each support 18 has the same shape.

  The clearance C between the apex 22 of the support 18 and the cylinder inner wall 19 is preferably 0.5 mm or more and 1.5 mm or less. The clearance C is a spatial distance in a state where the reaction extruder is stopped between the apex portion 22 of the support 18 of each screw piece 12, that is, the apex or a plane including the apex, and the cylinder inner wall 19 of the reaction extruder 10. More preferably, the thickness is 1.0 mm or more and 1.2 mm or less.

  The screw piece 12 preferably has at least one support 18 at L / D (screw shaft length (L) / screw shaft section diameter (D)) = 0.5 mm. What is necessary is just to combine each screw piece 12 according to the number of the support bodies 18 of each screw piece 12.

  At this time, even if pressure of the polymer compound is applied, the screw shaft 11 is supported by the support 18 of the screw piece 12 so as not to vibrate, and the polymer compound is not sheared.

  For example, when one screw piece 12 has two or more supports 18, if there is one screw piece 12, vibration of the screw shaft 11 can be suppressed by the support 18. When the number is one, the L / D of the portion filled with the material is small, and the filling time of the polymer compound is shortened. Therefore, it is preferable to provide two or more screw pieces 12.

  In addition, when there is one support body 18 for one screw piece 12, the screw shaft 11 cannot be supported by one screw piece 12, and therefore, a screw piece 12 provided with at least one support body 18 is further installed. There is a need to.

  An example of the arrangement of the screw pieces 12 is shown below. The following example is an example in which a plurality of screw pieces 12 are provided in the seal portion 15, and the first screw piece 12 a, the second screw piece 12 b, and the third screw piece 12 c are respectively provided from the hopper side screw piece 12 for explanation. Will be described. The number of screw pieces 12 is appropriately determined if necessary, but here it is limited to three for the sake of explanation. Further, in order to make the clearance between the support 18 and the cylinder wall surface easy to see, here, a case where the extruder is a single shaft will be described and an explanation will be given. A seal ring 17 is provided on the downstream side of the screw piece 12.

[Example when there is one support]
As shown in FIGS. 3 and 4, when there is one support 18 for one screw piece 12, the vibration of the screw shaft 11 due to the polymer compound pressure cannot be suppressed with only one screw piece 12. It is necessary to arrange a plurality of screw pieces 12.

  When only two screw pieces 12 are provided, the support bodies 18a and 18b of the first screw piece 12a and the second screw piece 12b are positioned symmetrically as shown in FIG. It is good to arrange like this.

  Even if the support 18 is a single screw piece 12, the structure is not limited to the case where three or more screw pieces 12 are provided, and any structure that can support the screw shaft 11 may be used. For example, as shown in FIG. 4, the first to third screw pieces 12a to 12c are arranged so that the supports 18a, 18b, and 18c are arranged every 90 degrees.

  In addition, since the screw piece 12 is fixed to the screw shaft 11 and each screw piece 12 moves in conjunction, the position of the fixed support 18 does not shift.

[Example when there are two or more supports]
As shown in FIGS. 5 to 8, when there are two or more supports 18 in one screw piece 12, the vibration of the screw shaft 11 can be suppressed to some extent even with one screw piece 12. The arrangement angle of the support body 18 of the second screw piece 12b and the subsequent screw pieces 12 is not particularly defined.

  For example, when there are four supports in one screw piece 12, as shown in FIG. 7, when the first and second screw pieces 12a and 12b are viewed from the side, the supports of the screw pieces 12a and 12b. 18a and 18b may be arranged in a line in parallel, and as shown in FIG. 8, when the first and second screw pieces 12a and 12b are viewed from the side, the first screw piece 12a is supported. The body 18a and the support body 18b of the second screw piece 12b may be arranged in a dotted manner so as to draw a spiral with respect to the screw shaft 11.

  Moreover, the number of the support bodies 18 of each screw piece 12 may differ if the vibration by the pressure of the polymer compound of the screw shaft 11 can be suppressed and the screw shaft 11 can be supported. However, when the support 18 is increased so much and the support 18 of each screw piece 12 is scattered so as to draw a spiral, even if the support 18 has no corners, shearing is applied to the polymer compound. You have to keep in mind that you will join.

  The number of the support bodies 18 of each screw piece 12 and the arrangement of the screw pieces 12 can be appropriately adjusted. However, the minimum support for suppressing the vibration of the screw shaft 11 due to the polymer compound pressure and supporting the screw shaft 11 is only required. The number and arrangement of the bodies 18 are assumed.

  The overall structure of the polymer compound processing apparatus having the mechanism described so far will be described.

  As shown in FIG. 9, the polymer compound processing apparatus 30 includes a reaction extruder 10 that generates a polymer product by reacting a polymer compound and a drug, and a polymer that is generated by the reaction extruder 10. The apparatus mainly includes a degassing extruder 31 for degassing the drug from the mixture of the compound and the drug.

  The reaction extruder 10 and the degassing extruder 31 may be single-screw or multi-screw, but a twin-screw extruder is preferable from the viewpoint of sealing properties such as a polymer compound. The twin-screw extruder is configured by providing a pair of screws in a cylinder so as to be rotatable in the same direction or in different directions.

  A hopper 32 for introducing a polymer compound is provided at the base of the reaction extruder 10, and a reaction tube 33 is connected to a discharge port at the tip of the reaction extruder 10. An injection portion 14 is provided in a cylinder between the hopper 32 and the discharge port of the reaction extruder 10.

  The injection unit 14 is connected to a drug tank 35 via a drug injection line 34. In the drug injection line 34, a drug injection pump 36 for pressurizing the drug and feeding it to the reaction extruder 10 and a drug heater 37 for heating the drug are arranged. The drug is heated to a high temperature and a high pressure by a drug injection pump 36 and a drug heater 37 and injected into the reaction extruder 10 in a supercritical or subcritical state.

  The reaction extruder 10 is provided with heating means (not shown) such as a jacket and a heater for keeping the inside of the cylinder at a predetermined temperature. The reaction extruder 10 is adjusted to a temperature and pressure at which the drug can maintain a supercritical or subcritical state.

  The reaction tube 33 keeps the supercritical or subcritical state and reacts the polymer compound with the drug. The tip (discharge port) of the reaction tube 33 is for deaeration through a discharge line 39 provided with a pressure adjusting mechanism 38 for reducing the mixture of the polymer compound and the drug discharged from the reaction tube 33 to near normal pressure. Connected to the inlet 40 of the extruder 31.

  A back vent 41 for degassing the drug from the mixture of the polymer compound and the drug is provided on the upstream side of the inlet 40 of the degassing extruder 31, and a back vent is provided on the downstream side of the inlet 40. Similar to 41, a front vent 42 for degassing the medicine is provided. The back vent 41 is provided with a vent box heater 43 for heating the back vent 41.

  A die 44 for discharging the degassed polymer product in the form of a strand is provided at the tip (discharge port) of the degassing extruder 31. A cooling water tank 45 for cooling the strand-shaped polymer product is disposed on the downstream side of the die 44, and the strand-shaped polymer product (strand 46) is cut downstream of the cooling water tank 45. A strand cutter 48 for pelletizing (forming pellets 47) is disposed.

  The back vent 41 and the front vent 42 are connected via a suction line 49 to a trapper 50 for trapping impurities in the medicine. The suction line 49 is provided with a tank pressure adjusting valve 51 for adjusting the pressure in the back vent 41 and the front vent 42.

  The trapper 50 is connected via a condensation line 52 to a condenser 53 that condenses and stores the medicine. In the condensing line 52, a vacuum pump 54 for vacuuming the medicine from the back vent 41 and the front vent 42 and condensing the vacuum sucked medicine into the condenser 53 is arranged. As the vacuum pump 54, it is preferable to use a dry pump that does not mix the sucked medicine and the liquid such as oil.

  A safety line 55 for opening the inside of the vent box is connected to each of the back vent 41 and the front vent 42, and a safety valve 56 is provided in the safety line 55.

  An example of a method for treating a polymer compound using the polymer compound treatment apparatus 30 is as follows. A silane-crosslinked polyethylene is introduced as a polymer compound from the hopper 32 into the reaction extruder 10 and is supplied from the drug injection pump 36. Alcohol as a medicine is sent out and heated by a medicine heater 37 to be in a supercritical or subcritical state, which is injected from the injection section 14 into the cylinder of the reaction extruder 10 and connected to the reaction extruder 10 and this. In the reaction tube 33, the silane-crosslinked polyethylene and the alcohol are reacted while maintaining a supercritical or subcritical state.

  Thereafter, the mixture of the thermoplasticized reaction product and the reacted alcohol is depressurized to near normal pressure via the pressure adjusting mechanism 38, and is converted into the reaction product and the reacted alcohol in the degassing extruder 31. To be separated.

  The reaction product is extruded as a strand 46 from a die 44 of a degassing extruder 31, cooled with water through a cooling water tank 45, and then pelletized 47 by a strand cutter 48.

  For the alcohol, a trapper 50 for removing impurities in the waste alcohol from the back vent 41 and the front vent 42 connected to the degassing extruder 31, a dry type in which the sucked waste alcohol and liquid such as oil do not mix. It passes through the vacuum pump 54 and is condensed in the condenser 53.

  In addition to the above-mentioned silane-crosslinked polyethylene, the polymer compound to be treated using the polymer compound treatment apparatus 30 includes a crosslinked polymer, a polymer having no thermosetting property or thermoplasticity such as plastic or rubber, and lignin. Natural polymers such as cellulose, protein, etc., as well as mixtures of synthetic and natural polymers, mainly polymer compounds such as shredder dust, mixed with other materials, and combined with appropriate drugs It works particularly well for what you do.

  By using the present invention, since there is no thermoplasticity, recycled polyethylene obtained from silane-crosslinked polyethylene, which has not undergone much material recycling, can have the same tensile properties and number average molecular weight as base polyethylene. It becomes.

  Naturally, this recycled polyethylene can be used in a wide range of applications, and depending on the application, it may not be necessary to add a virgin material to compensate for the characteristics, so it can be expected to have a significant effect on the environment and economy. .

  Further, when the polymer compound and the subcritical or supercritical fluid are brought into contact with each other using a reaction extruder, it works effectively when it is desired to prevent the polymer compound from being excessively sheared even under high pressure.

  Therefore, according to the present invention, the kneading disk is not used for the screw piece of the reaction extruder, the screw piece that rotates integrally with the screw shaft of the reaction extruder is not sheared on the polymer compound, and Since it has a structure that can withstand high temperature and pressure, a polymer product having mechanical properties and molecular weight almost equal to that of a virgin material can be produced.

Example 1
By decomposing silane-crosslinked polyethylene (gel fraction 40%) prepared by the formulation shown in Table 1 with supercritical methanol under the conditions shown in Table 2 using the polymer compound processing apparatus 30 shown in FIG. The recycled polyethylene shown in Table 3 was obtained.

  Here, the reaction extruder 10 and the degassing extruder 31 are a twin screw extruder having a screw diameter of 30 mm (L / D of the reaction extruder 10 = 52.5, L / D of the degassing extruder 31). = 32.0) was used.

  Supply part 13 (L / D = 20.75) using full flight 20 from the upstream side of the reaction extruder, screw piece part (L / D = 2.5) and seal ring part shown in FIGS. A screw is configured in the order of a seal portion 15 (L / D = 3.5) using L / D = 1.0) and a transport portion 16 (L / D = 28.25), and methanol is introduced from the upstream side of the extruder. It injected from the extruder cylinder in the position of L / D = 27.25.

  The silane-crosslinked polyethylene was subjected to continuous treatment of 40 kg / h for 8 hours for 20 cycles (total of 160 hours for treatment of 6.4 t). As the screw piece 12, tool steel made of iron base (containing chromium, cobalt, etc.) and hardened by quenching was used.

  By comparing the gel fraction, tensile strength, elongation, and number average molecular weight of this regenerated polyethylene with the base polyethylene in Table 1, the effect of shear on the molecules was evaluated.

  Further, the screw was pulled out after 20 cycles, and the external appearance of the screw piece and the extruder cylinder wall surface was visually observed to confirm whether the screw piece and the extruder cylinder wall surface were worn or damaged.

  Judgment is that the gel fraction of recycled polyethylene is less than 10%, the cross-linking and cutting reaction proceeds sufficiently, and the values of tensile strength, elongation, number average molecular weight are 90% or more of base polyethylene, If there is no wear / breakage, it is acceptable (O), if the gel fraction is 10% or more, or if any of the evaluated properties is less than 90% of the base polyethylene, or the treated screw piece is worn. -The case where there was breakage was considered as a disqualification (x).

The gel fraction was extracted in hot xylene at 110 ° C. for 24 hours in accordance with JIS C 3005. Thereafter, the weight after vacuum drying at 80 ° C. for 4 hours was weighed, and the gel fraction was calculated by the following formula from the ratio to the weight before extraction.
Gel fraction (%) = (weight after extraction (g) / weight before extraction (g)) × 100

  In the tensile test, a product press-molded into a 1 mm thick sheet according to JIS C 3605 was punched into the shape of dumbbell No. 3, and 200 mm / min. The shopper type tensile tester was used at a speed of

  The number average molecular weight was measured by dissolving the sample in O-dichlorobenzene and using high temperature GPC (gel permeation chromatography).

  In addition, a residual rate shows the ratio with respect to the physical-property value of base polyethylene in Table 1. A hatched portion indicates a determination item that is rejected.

  In Example 1, as shown in FIGS. 1 and 2, three pieces each having four support bodies 18 on one screw piece 12 in the piece portion are arranged with respect to one axis. From Table 3, in Example 1, the gel fraction is 0%, the tensile strength, elongation, and number average molecular weight of the recycled polyethylene are all 90% or more of the base polyethylene. No damage was seen.

  From this, the cross-linking and cutting reaction has proceeded sufficiently and the characteristic value is 90% or more of the base polyethylene, so that it is understood that excessive shear is not applied to the silane cross-linked polyethylene in the reaction extruder 10. It was.

  It is considered that there is no problem with the pressure resistance of the screw piece 12 under these conditions. Moreover, since the wall surface of the extruder cylinder is not damaged after the experiment, it is considered that there is no problem with the interference between the screw piece 12 and the cylinder.

  The screw piece 12 having the projecting support 18 for relieving the stress applied to the torpedo piece on the outer surface of the torpedo piece is not limited to the shape shown in FIG. 1, and recycled polyethylene is equivalent to the base polyethylene. As long as the tensile properties of the resin and the number average molecular weight are low, the shear applied to the silane-crosslinked polyethylene is small, and the screw piece 12 is not deformed under high pressure and does not wear or break.

  In Example 1, a twin-screw extruder was used, but the reaction extruder 10 is not limited to this, and can be developed to a single-screw extruder or a multi-screw extruder.

  In Example 1, although the silane bridge | crosslinking polyethylene was used as a high molecular compound and it was set as the example decomposed | disassembled by alcohol, it is not limited to this.

(Comparative Example 1)
As shown in FIG. 10, the same experiment as in Example 1 was performed using a kneading disk 60 in place of the screw piece 12 shown in FIG. 1 in the seal portion 15 of the reaction extruder 10 shown in FIG. It is what I did.

  From Table 3, in Comparative Example 1, no abrasion or breakage was observed on the kneading disk 60 or the extruder cylinder wall after treatment, but the tensile strength and number average molecular weight of recycled polyethylene were less than 90% of the base polyethylene. I found out.

  Since the gel fraction is 0%, it is considered that although the crosslinking and cutting reaction has proceeded sufficiently, the tensile strength and the number average molecular weight have decreased compared to the base polyethylene due to excessive shearing.

(Comparative Example 2)
As shown in FIG. 11, in the seal part 15 of the reaction extruder 10 shown in FIG. 2, the full flight 20 of the supply part 13 is extended except for the screw piece 12 shown in FIG. L / D = 1.0) is provided in the latter half of the seal portion 15), and is the same experiment as in Example 1.

  From Table 3, in Comparative Example 2, the gel fraction of the recycled polyethylene was 0%, and the tensile strength, elongation, and number average molecular weight all had characteristics of 90% or more of the base polyethylene. However, when the full flight 20 after the treatment was observed, the tip of the blade 21 of the full flight 20 connected to the seal ring 17 was broken. I found out.

  Further, no particular damage was found on the wall surface of the extruder cylinder. Accordingly, it was found that the full flight 20 cannot be used as an alternative to the screw piece 12 shown in FIG. 1 because the blade 21 is damaged by the pressure of the polymer compound staying in the seal portion 15.

(Comparative Example 3)
As shown in FIG. 12, in the seal portion 15 of the reaction extruder 10 shown in FIG. 2, a torpedo piece 70 (ordinary cylindrical piece, protrusion-like support 18 is used instead of the screw piece 12 shown in FIG. 1. None), and a torpedo piece 70 (L / D = 2.5) and a seal portion 15 (L / D = 3.5) composed of a seal ring portion (L / D = 1.0) The same experiment as in No. 1 was performed.

  From Table 3, in Comparative Example 3, the gel fraction of the recycled polyethylene was 0%, and the tensile strength, elongation, and number average molecular weight all had characteristics of 90% or more of the base polyethylene. Was sufficiently advanced and had the same characteristics as the base polyethylene, but the operation was stopped because an abnormal noise was generated from the reaction extruder 10 in the fifth cycle.

  When the torpedo piece 70 after the operation was stopped was observed, it was found that the tip of the blade 21 of the full flight 20 connected to the torpedo piece 70 was worn and the wall surface of the extruder cylinder was damaged. The pressure of the polymer compound staying in the seal portion 15 is applied to the torpedo piece 70, and the torpedo piece 70 has a large clearance C of about 3 mm to 4 mm and does not have the support 18. It is considered that abnormal noise was generated because the tip of the blade 21 of the flight 20 interfered with the wall surface of the extruder cylinder.

  From the above, it was found that when the kneading disk 60 is used for the seal portion 15, the recycled polyethylene has a significant decrease in tensile strength and number average molecular weight as compared with the base polyethylene.

  Moreover, when the seal part 15 is comprised only by the seal ring 17, the front-end | tip part of the blade | wing 21 of the full flight 20 in front of the seal ring 17 will be missing by the pressure of a polymer compound, and it cannot be used for the seal part 15 in this application. I understood that.

  Further, when a normal torpedo piece 70 is used instead of the screw piece 12 shown in FIG. 1, the screw shaft 11 vibrates, the tip of the blade 21 of the full flight 20 of the supply unit 13 wears, and the extruder cylinder. It turned out that the operation was difficult because the wall was damaged.

DESCRIPTION OF SYMBOLS 10 Reaction extruder 11 Screw shaft 12 Screw piece 12a 1st screw piece 12b 2nd screw piece 12c 3rd screw piece 13 Supply part 14 Injection | pouring part 15 Sealing part 16 Conveyance part 17 Seal ring 18 Support body 18a 1st screw piece support Body 18b Second screw piece support 18c Third screw piece support 19 Cylinder inner wall 20 Full flight 21 Blades 22 Support apex 30 Polymer compound processing device 31 Degassing extruder 32 Hopper 33 Reaction tube 34 Drug injection Line 35 Drug tank 36 Drug injection pump 37 Drug heater 38 Pressure adjustment mechanism 39 Discharge line 40 Input port 41 Back vent 42 Front vent 43 Vent box heater 44 Die 45 Cooling water tank 46 Strand 47 Pellet 48 Strand cutter 49 Suction In 50 trapper 51 So圧 regulating valve 52 condensate line 53 condenser 54 vacuum pump 55 safety line 56 a safety valve 60 kneading disc 61 surface 70 Topidopisu C Clearance

Claims (6)

In a method for treating a polymer compound in which a polymer compound and a subcritical or supercritical fluid drug are reacted in a reaction extruder to produce a polymer product,
A method of treating a polymer compound, characterized in that a screw piece that rotates integrally with a screw shaft of the reaction extruder has a structure that can withstand high temperature and pressure without shearing the polymer compound. In a processing apparatus for a high molecular compound in which a high molecular compound and a subcritical or supercritical fluid agent are reacted in a reaction extruder to generate a high molecular product,
The reaction extruder includes a supply unit for the polymer compound, an injection unit for injecting the drug, a seal unit for preventing the drug from flowing back to the supply unit side, the polymer compound, and the A transport unit that transports a mixture of medicines to the downstream side of the extruder,
The seal portion comprises a screw piece that rotates integrally with a screw shaft of the reaction extruder, and a seal ring that is provided on the downstream side of the extruder with respect to the screw piece,
A processing apparatus for a polymer compound, wherein the screw piece has a structure capable of withstanding high temperature and pressure without shearing the polymer compound.   When the pressure of the polymer compound is applied to the seal portion, the surface of the screw piece approaches or comes into contact with the cylinder inner wall of the reaction extruder, supports the screw shaft, and vibrates or deforms the screw shaft. The polymer compound processing apparatus according to claim 2, wherein a projecting support having a curved shape is formed.   The apparatus for treating a polymer compound according to claim 3, wherein the clearance between the apex of the support and the inner wall of the cylinder when the reaction extruder is stopped is 0.5 mm or more and 1.5 mm or less.   5. The polymer compound according to claim 3, wherein the screw piece has at least one support body at L / D (screw shaft length (L) / screw shaft cross-sectional diameter (D)) = 0.5 mm. Processing equipment.   The processing apparatus for a polymer compound according to any one of claims 2 to 5, wherein the reaction extruder is a twin screw extruder.