Peroxide reaction method and peroxide reaction device using extruder

Abstract

This invention is to improve the reaction efficiency of a peroxide introduced into a cylinder compared with conventional art. In the peroxide reaction method and peroxide reaction device using an extruder according to this invention, in which a peroxide and a raw material such as a synthetic resin, a natural resin, and an elastomer are introduced into a cylinder of the extruder, wherein the raw material and the peroxide are reacted with each other in the cylinder, the raw material is introduced from a raw material supply hopper, the peroxide is introduced from a downstream side of the raw material supply hopper, and the temperature of the raw material in a peroxide introduction portion is adjusted to a temperature lower than the one-minute half-life temperature of the peroxide.

Claims

1. A peroxide reaction method comprising: providing an extruder comprising a cylinder, wherein the extruder has at least a solid transportation portion, a plasticization and kneading portion, and a melt transportation portion formed in the cylinder from an upstream side to a downstream side; introducing a raw material into the extruder from a raw material supply hopper, wherein the raw material is at least one selected from the group consisting of a synthetic resin, a natural resin, and an elastomer; introducing a peroxide into the extruder at at least one peroxide introduction portion provided on a downstream side of the raw material supply hopper, wherein at least one of the at least one peroxide introduction portions is positioned on an upstream side of an upstream position of both the melt transportation portion and the plasticization and kneading portion; and adjusting a temperature of the raw material in the peroxide introduction portion to a temperature lower than a one-minute half-life temperature of the peroxide by adjusting the temperature of the cylinder, wherein the peroxide and the raw material are introduced individually into the cylinder of the extruder without being mixed together in advance, and wherein the raw material and the peroxide react with each other in the cylinder.

2. The peroxide reaction method using an extruder according to claim 1, wherein the extruder is a twin screw extruder.

3. The peroxide reaction method using an extruder according to claim 1, wherein the raw material is polypropylene or polyethylene.

4. The peroxide reaction method using an extruder according to claim 1, wherein the one-minute half-life temperature of the peroxide is from 50 C. to 300 C.

5. The peroxide reaction method using an extruder according to claim 1, wherein the one-minute half-life temperature of the peroxide is from 100 C. to 200 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a sectional view showing a configuration of an extruder with which to implement a peroxide reaction method and a peroxide reaction device using an extruder according to this invention.

(2) FIG. 2 is a sectional view showing the configuration of FIG. 1 in another condition.

(3) FIG. 3 is a characteristic diagram showing a relationship between a temperature of a peroxide introduction portion of the extruder and an MFR of a product.

EMBODIMENTS OF THE INVENTION

(4) A peroxide reaction method and a peroxide reaction device using an extruder according to this invention are an improvement in a reaction efficiency between the peroxide and the raw material by introducing a peroxide and a raw material are introduced into a cylinder independently of each other rather than being mixed together in advance on the exterior of the cylinder.

Embodiments

(5) A preferred embodiment of a peroxide reaction method and a peroxide reaction device using an extruder according to this invention will be described below together with the drawings.

(6) FIG. 1 shows a preferred embodiment of the peroxide reaction method and peroxide reaction device using an extruder according to this invention, wherein a liquid peroxide is introduced into a cylinder.

(7) In FIG. 1, a reference numeral 1 denotes a cylinder of a single screw or twin screw extruder 2 in which a raw material and the peroxide are reacted with each other, a single-shaft or twin-shaft screw 3 being disposed in the cylinder 1 to be freely rotatable. Note that a die 7 having an extrusion hole 7a is provided on a tip end serving as a downstream side 1B of the cylinder 1.

(8) A reduction gear 5 and a rotary driving body (constituted by a motor or the like) 6 are connected to the cylinder 1 via a connecting member 4.

(9) A screw shaft 3A of the screw 3 is connected to an output side of the reduction gear 5 and configured such that the screw 3 can be rotated via the reduction gear 5 by rotating the rotary driving body 6.

(10) The cylinder 1 is divided into three regions, namely a solid transportation portion 10, a plasticization and kneading portion 11, and a melt transportation portion 12, from an upstream side 1A toward the downstream side 1B.

(11) The solid transportation portion 10 is provided with a raw material supply hopper 30 for introducing a raw material 20 constituted by one of a synthetic resin, a natural resin, an elastomer, or the like into the cylinder 1.

(12) First, second, and third liquid addition pumps 31, 32, 33 are disposed independently of each other in the cylinder 1, and a first peroxide introduction portion 31A of the first liquid addition pump 31 is positioned at a downstream position 40 of the solid transportation portion 10.

(13) A second peroxide introduction portion 32A of the second liquid pump 32 is positioned at a substantially central position 41 of the plasticization and kneading portion 11.

(14) A third peroxide introduction portion 33A of the third liquid pump 33 is positioned at an upstream position 42 of the melt transportation portion 12. The upstream position 42 is a position close to the plasticization and kneading portion 11. Note that the respective peroxide introduction portions 31A, 32A, 33A are each formed in a structure having a pipe including a check valve attached within a hole, not shown in the figure, formed in the cylinder 1, for example.

(15) Next, an operation of the peroxide reaction method and peroxide reaction device using an extruder according to this invention will be described.

(16) First, the raw material 20, which is introduced into the cylinder 1 of the extruder 2 from the raw material supply hopper 30, is conveyed to the downstream side 1B by the solid transportation portion 10 by rotating the screw 3, and then plasticized and kneaded in the plasticization and kneading portion 11.

(17) In this condition, the first to third liquid pumps 31 are operated by a predetermined program of a control portion, not shown in the figure, whereby liquid peroxide is introduced into the cylinder 1 from one or all of the first, second, and third peroxide introduction portions 31A, 32A, 33A so that the peroxide 50A and the raw material 20 are melted and kneaded in the cylinder 1 and a reaction occurs.

(18) This reaction can be used to adjust the viscosity and other properties of the raw material 20. Note that the liquid peroxide 50A may be used as is, or may be used after being diluted in oil or the like.

(19) If the peroxide 50A is constituted by a liquid or a liquid mixture, as in FIG. 1, the peroxide 50A is introduced into the cylinder 1 via the first, second, and third liquid addition pumps 31, 32, 33 respectively having the peroxide introduction portions 31A, 32A, 33A. However, in another embodiment shown in FIG. 2, a solid peroxide 50 is used instead of the liquid peroxide 50A, and accordingly, first to third volumetric supply devices 51 to 53 constituted by any of a conventional screw feeder, belt feeder, table feeder, or the like are used to introduce the solid peroxide 50 into the cylinder 1, whereby the solid peroxide 50 can be introduced into the cylinder 1 via the first to third peroxide introduction portions 31A, 32A, 33A of the cylinder 1. Note that in FIG. 2, portions that are identical to FIG. 1 have been allocated identical reference numerals, and description thereof has been omitted to avoid duplication.

(20) The peroxide 50, 50A can be introduced using the upstream side, the downstream side, or any of the aforesaid locations of the plasticization and kneading portion 11, as in the configurations shown in FIGS. 1 and 2, and a plurality of locations may be used together. The cylinder 1 is constituted by a plurality of cylinder segments (not shown), and a temperature adjustment function is obtained by providing each cylinder segment with heating means such as an electric heater, a steam heater, an oil heater, or a hot water heater, and cooling means realized by supplying a cooling medium such as cooling water.

(21) The introduction portions 31A, 32A, 33A for the peroxide 50, 50A can be adjusted to a temperature lower than a one-minute half-life temperature of the peroxide 50, 50A, which is a feature of this invention, using the aforesaid temperature adjustment function of the cylinder 1 or by adjusting the shape of the screw. Further, it is known that a reaction speed of the peroxide 50, 50A is temperature-dependent, or in other words that the reaction speed increases as the temperature rises. Furthermore, the reaction of the peroxide 50, 50A proceeds over time, and therefore, to ensure that the peroxide 50, 50A is used effectively in the reaction, it is important to adjust the reaction speed so that the reaction is completed within a period extending from the point at which the peroxide 50, 50A is introduced into the cylinder 1 of the extruder to a point at which the peroxide 50, 50A is discharged to the exterior of the cylinder 1, or in other words within a residence time. Moreover, as a criterion for completing the reaction, it is important to set the temperature at a temperature at which the peroxide decreases by half four times within the residence time for a portion wherein peroxide reacts, or to adjust the residence time to a residence time within which the peroxide decreases by half four times at a temperature of a portion wherein the peroxide reacts.

(22) Hence, if the temperature of the respective peroxide introduction portions 31A, 32A, 33A is set excessively high, a problem occurs that the peroxide 50, 50A starts reacting before being dispersed sufficiently through the raw material 20 or the like and a reaction rate with the raw material 20 is reduced. According to this invention, therefore, the temperature of the respective peroxide introduction portions 31A, 32A, 33A is adjusted so as to be lower than the one-minute half-life temperature of the used peroxide 50, 50A, and in so doing, the aforesaid reduction in the reaction rate can be suppressed, or in other words the reaction efficiency can be improved. Hence, increasing the reaction speed by raising the temperature on the downstream side of the respective peroxide introduction portions 31A, 32A, 33A is effective as means for increasing the reaction rate, and therefore the reaction efficiency, within the limited residence time in the cylinder of the extruder.

EXAMPLE

(23) Next, results of a reaction test performed using the peroxide reaction method and peroxide reaction device using an extruder according to this invention will be described.

(24) In the example, the device and raw material described below were used.

(25) Extruder: twin screw extruder, CMP69 (manufactured by The Japan Steel Works Ltd.)

(26) Inner diameter of extruder cylinder: 69 mm

(27) Extruder L/D (ratio of total screw length to cylinder inner diameter): 35 L/D

(28) Raw material: polypropylene (MFR=2.0)

(29) Raw material throughput: 320 kg/h

(30) Peroxide: organic peroxide

(31) Peroxide addition amount: 1000 ppm

(32) The raw material temperature in the respective peroxide introduction portions 31A, 32A, 33A was varied using the temperature adjustment function of the cylinder and by adjusting the shape of the screw. In this example, the peroxide 50 or 50A has an effect of increasing the MFR by reacting with the raw material 20. Therefore, by measuring the MFR [g/min] of a product, the reaction rate of the peroxide 50 or 50A can be estimated. FIG. 3 shows the temperature of the peroxide introduction portions 31A, 32A, 33A and the MFR of a manufactured product. It is clear that the MFR becomes small where the temperature of the peroxide introduction portions 31A, 32A, 33A exceeds the one-minute half-life temperature=174 C.

(33) The gist of the peroxide reaction method and peroxide reaction device using an extruder according to this invention is as follows.

(34) In the peroxide reaction method and peroxide reaction device using an extruder, in which the peroxide 50 or 50A and the raw material 20 constituted by one of a synthetic resin, a natural resin, and an elastomer are introduced individually into the cylinder 1 of the extruder 2, the cylinder 1 having a temperature adjustment function, without being mixed together in advance, wherein the raw material 20 and the peroxide 50 or 50A are reacted with each other in the cylinder 1, characterized in that: the raw material 20 is introduced from the raw material supply hopper 30; the peroxide 50 or 50A is introduced from the peroxide introduction portions 31A, 32A, 33A provided on the downstream side of the raw material supply hopper 30; and the temperature of the raw material 20 in the peroxide introduction portions 31A, 32A, 33A is adjusted to a temperature lower than the one-minute half-life temperature of the peroxide 50 or 50A using at least the temperature adjustment function. Further, the method and device are characterized in that, at least the solid transportation portion 10, the plasticization and kneading portion 11, and the melt transportation portion 12 are formed in the cylinder 1 from the upstream side, and the peroxide introduction portions 31A, 32A, 33A are positioned on an upstream side of an upstream position 42 of the melt transportation portion 12. Further, the method and device are characterized in that the extruder 2 is a twin screw extruder. Further, the method and device are characterized in that the raw material 20 is polypropylene or polyethylene. Further, the method and device are characterized in that the one-minute half-life temperature of the peroxide 50 or 50A is from 50 C. to 300 C. Further, the method and device are characterized in that the one-minute half-life temperature of the peroxide 50 or 50A is from 100 C. to 200 C. Further, the method and device are characterized in that, if a melting point of the resin serving as the raw material 20 is higher than the one-minute half-life temperature of the peroxide 50 or 50A, the peroxide introduction portion 31A is positioned on an upstream side of the plasticization and kneading portion 11.

INDUSTRIAL APPLICABILITY

(35) In the peroxide reaction method and peroxide reaction device using an extruder according to this invention, a peroxide is introduced into a cylinder from a downstream side of a raw material supply hopper, whereupon a raw material temperature in a peroxide introduction portion is adjusted to a lower temperature than a one-minute half-life temperature of the peroxide. In so doing, a reduction in a reaction rate of the peroxide can be suppressed and reaction efficiency can be improved.

REFERENCE SIGNS LIST

(36) 1 Cylinder

(37) 1A Upstream side

(38) 1B Downstream side

(39) 2 Extruder

(40) 3 Screw

(41) 3A Screw shaft

(42) 4 Connecting member

(43) 5 Reduction gear

(44) 6 Rotary driving body (motor)

(45) 10 Solid transportation portion

(46) 11 Plasticization and kneading portion

(47) 12 Melt transportation portion

(48) 20 Raw material

(49) 30 Raw material supply hopper

(50) 31, 32, 33 First, second, and third liquid addition pumps

(51) 31A, 32A, 33A First, second, and third peroxide introduction portions

(52) 40 Downstream position

(53) 41 Central position

(54) 42 Upstream position

(55) 50A Peroxide (liquid)

(56) 50 Solid peroxide