JP2006225535A - Method for producing thermoplastic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a thermoplastic resin composition, capable of preventing the scattering of an additive to the outside of a solid phase polymerization vessel accompanying with the decrease of pressure in the solid phase polymerization. <P>SOLUTION: This method for producing the thermoplastic resin composition is characterized in that a tablet-formed additive is used in one or a plural number of additives used in a rotary batch type solid phase polymerization device under a reduced pressure, also among the composition of the additives, the melting point of at least one of them is at or less than the temperature for the solid phase polymerization, the ratio of the diameter to height of the tablet-formed additive is 0.5-2.5 and also the breaking strength of the tablet-formed additive is 3-15 kg. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a method for producing a thermoplastic resin composition in which a heat-resistant agent, a release agent or the like (hereinafter referred to as an additive) is attached to the surface of a thermoplastic resin composition. More specifically, since the shape of the additive is a tablet, there is little scattering of the additive outside the tank due to decompression during solid-phase polymerization, and accordingly, the decompression system is prevented from clogging, and the number of maintenance can be reduced. This is a method for producing a thermoplastic resin composition.

  Usually, the solid phase polymerization of a thermoplastic resin composition is generally performed by filling a small resin lump called pellets into a solid phase polymerization tank and using a batch or continuous apparatus under reduced pressure or inert gas flow at a high temperature. It is known to be done. Such a solid phase polymerization apparatus for a thermoplastic resin composition has been conventionally used, and examples thereof can be found in Patent Documents 1 and 2, for example.

  The rotary batch solid-phase polymerization apparatus under reduced pressure is suitable for small-quantity, multi-product production, and the thermoplastic resin composition pellets are heated by a heating medium in a jacket stretched around the rotary batch solid-phase polymerization apparatus under reduced pressure. Therefore, it is possible to fix the additive on the pellet surface by utilizing this. However, since the rotary batch solid-phase polymerization apparatus under reduced pressure performs solid-state polymerization under reduced pressure, the additive scatters out of the solid-phase polymerization tank, thereby causing the clogging of the decompression system piping and the malfunction of the reduced-pressure generator. There's a problem.

  To prevent powder scattering outside the solid-phase polymerization tank, there is a method of adding and mixing the additive into the solid-phase polymerization tank after the completion of the solid-phase polymerization. There is a problem that it cannot be squeezed out and falls off during transportation such as air transportation, or accumulates on the bottom of the packaging bag.

To prevent the additive from falling off, there is a method using a spreading agent such as silicone or propylene glycol. However, when the drying is performed before extrusion or molding, the spreading agent volatilizes and the filter of the dryer is used. There is a problem that it adheres to the surface and causes blockage.
JP 49-16794 A JP 56-84719 A

  The objective of this invention is providing the manufacturing method of the thermoplastic resin composition which can prevent scattering of the additive to the exterior of a solid phase polymerization tank accompanying the pressure reduction at the time of solid phase polymerization.

The method for producing the thermoplastic resin composition of the present invention comprises:
(1) In one or a plurality of additives used for polymerization in a rotary batch solid-phase polymerization apparatus under reduced pressure, the additive is in the form of a tablet, and at least one melting point of the additive composition Is a method for producing a thermoplastic resin composition, characterized in that the temperature is lower than the solid phase polymerization temperature, preferably (2) the ratio of the diameter and height of the tablet-like additive is 0.5 to 2.5 (1) The method for producing a thermoplastic resin composition according to (1), more preferably (3) the breaking strength of the tablet-like additive is in the range of 3 to 15 kg. The method for producing a thermoplastic resin composition according to (1) or (2).

  In the method for producing the thermoplastic resin composition of the present invention, since there is little scattering of the additive outside the solid phase polymerization tank due to the pressure reduction during the solid phase polymerization, the pressure reducing system piping is hardly clogged and the generation of the reduced pressure occurs. Device failures can also be prevented. As a result, the number of equipment maintenance is reduced and production can be increased.

  Hereinafter, an apparatus and a method according to an embodiment of the present invention will be described in detail using the drawings. FIG. 1 is a schematic front view of a rotary batch type solid phase polymerization apparatus under reduced pressure. This apparatus has a double-conical solid-phase polymerization tank 1, a heating jacket 2 of the solid-state polymerization tank 1, a raw material thermoplastic resin composition pellet inlet and a solid-phase polymerization finished pellet outlet 3, and an additive. A mouth 4 and a mesh filter 5 are provided. The solid phase polymerization tank 1 is connected to a decompression system pipe 6, a collection pot 7, a vacuum generator 8, a solid phase polymerization tank rotating motor 9, and the like.

  In the solid-phase polymerization method of the present invention, first, pellets and tablet-like additives are filled in a double-cone solid-phase polymerization tank, and pressure reduction is started. Even if decompression is performed, the additive is in a tablet shape larger than the mesh filter opening, so that it is prevented from scattering out of the tank. Can be prevented. After the pressure is reduced to a specified value, the solid phase polymerization tank is started to rotate, a heating medium is passed through a jacket installed around the solid phase polymerization tank, and heating is started. As the pellet temperature increases, the tablet-like additive is also heated, so that when the temperature becomes equal to or higher than the melting point of the composition of the tablet-like additive, it gradually disintegrates and adheres to the pellet.

  The term "fixation" as used herein means that the molten additive adheres to the pellet surface and then impregnates inside the pellet, and in the case of an additive that does not melt, it adheres to the pellet surface via the molten additive. . Therefore, it cannot be said that it is fixed only by an additive that does not melt.

In the solid phase polymerization in the method for producing a thermoplastic resin composition of the present invention, in FIG. 1, first, the raw material thermoplastic resin composition pellets are supplied to the solid phase polymerization tank 1 from the pellet inlet 3 by about 1/5 of the prescribed amount. And a prescribed amount of tablet-like additive is charged from the additive inlet 4. After charging the additive, the remaining raw material thermoplastic resin composition pellets are filled into the solid phase polymerization tank 1 from the pellet charging port 3. After completion of filling, the solid phase polymerization tank 1 is depressurized by the vacuum generator 8.
After reaching the specified degree of pressure reduction, the solid phase polymerization tank rotation motor 9 starts to rotate the solid phase polymerization tank 1, and then the heating jacket 2 is heated to start heating.

  When the thermoplastic resin composition pellets are heated by the heating jacket 2, the tablet-like additive is also heated, so that it gradually melts and adheres to the thermoplastic resin composition pellets.

After reaching a predetermined degree of polymerization, the supply of the heating medium to the heating jacket 2 is stopped, and a refrigerant is supplied instead to cool the thermoplastic resin composition pellets.
When the thermoplastic resin composition pellets are cooled to the specified temperature, the supply of the refrigerant and the vacuum generator 8 are stopped, and the solid phase polymerization tank 1 is returned to normal pressure with nitrogen, and then the pellets are extracted from the outlet 3.

  Examples of the thermoplastic resin composition to which the present invention can be applied include polyamides typified by polycapramide and polyhexamethylene adipamide, copolymers thereof, polyesters typified by polyethylene terephthalate and polybutylene terephthalate, and copolymers thereof. Although it is a polymer etc., it is applicable also to other thermoplastic resin compositions.

  Examples of the method for producing the tablet additive include a compression method and a melting method, and the compression method is preferably used.

  The tablet shape is not particularly limited, but a spherical shape or a cylindrical shape is preferable. Further, the size of the tablet needs to be larger than the opening of the filter so as not to scatter out of the tank from the mesh filter. However, if the ratio of the diameter and height of the tablet is too large, it will be easily disintegrated in the solid phase polymerization tank during transportation and storage, so the ratio of diameter to height is in the range of 0.5 to 2.5. Preferably there is.

  If the strength of the tablet is low, it will be easily disintegrated in the solid phase polymerization tank during transportation and storage, and if it is high strength, it will be difficult to disintegrate in the solid phase polymerization tank. It is preferable that

  The thermoplastic resin composition obtained according to the present invention is used as it is or mixed with a colorant for injection molding or extrusion molding, or melted with a reinforcing material such as glass fiber, a rubber component, a colorant, a heat-resistant agent, etc. It can be used after kneading.

  Hereinafter, the present invention will be specifically described with reference to examples. In addition, the amount of powder scattered outside the tank used in the examples was determined from the weight of the powder collected in the collection pot installed in the middle of the decompression system pipe. The present invention is not limited to the embodiment.

Example 1
1,000 kg of polyester elastomer pellets are charged into a rotary batch-type solid-phase polymerization apparatus having a structure shown in FIG. 1, and then tablet-like additives (diameter: 7 mm, height: 6 mm, breaking strength: 7 kg, tablet composition: Polyester elastomer pellets having a melting point of 158 ° C. and 176 ° C. (equal ratio mixture) of 25 kg and 7,000 kg were added. After completion of the charging, the vacuum generator 8 was used to reduce the pressure, and after reaching the specified pressure reduction degree, the solid phase polymerization tank rotation motor 9 was started and the solid phase polymerization tank 1 started rotating. Next, steam was supplied to the heating jacket 2 and the temperature increase was started. The temperature was increased so that the pellet temperature became 180 ° C., and the solid temperature polymerization was performed while maintaining the temperature as it was. After reaching a predetermined degree of polymerization, the steam supply to the heating jacket 2 was stopped, and cooling water was poured to cool the pellets. When the pellet temperature reached 90 ° C., the cooling water and the vacuum generator 8 were stopped, the solid phase polymerization tank 1 was returned to normal pressure with nitrogen, and then discharged from the pellet discharge port 3. The powder collected by the collection trap was 0.01 kg.

Comparative Example 1
Solid phase polymerization was carried out in the same manner as in Example 1 except that a powder additive was used instead of the tablet additive. The powder recovered by the collection trap was 2 kg.

  As described above, it was confirmed that by using the tablet-like additive, the powder outside the tank almost disappeared.

1 is a schematic front view of a rotary batch type solid phase polymerization apparatus under reduced pressure that can be preferably used in the present invention.

Explanation of symbols

1: Solid phase polymerization tank 2: Heating jacket 3: Raw material thermoplastic resin pellet inlet / solid weight pellet outlet 4: Additive inlet 5: Mesh filter 6: Decompression system pipe 7: Collection pot 8: Vacuum Generator 9: Motor for rotating solid phase polymerization tank

Claims (3)

In one or a plurality of additives used for polymerization in a rotary batch type solid phase polymerization apparatus under reduced pressure, the shape of the additive is a tablet, and at least one melting point of the additive composition is a solid phase. The manufacturing method of the thermoplastic resin composition characterized by being below polymerization temperature. The method for producing a thermoplastic resin composition according to claim 1, wherein the ratio of the diameter and height of the tablet-like additive is in the range of 0.5 to 2.5. The method for producing a thermoplastic resin composition according to claim 1 or 2, wherein the tablet additive has a breaking strength of 3 to 15 kg.

Images