JP2000108191A - Manufacture of lengthy article of thermoplastic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a lengthy article of a thermoplastic resin having a small outer diameter change even in the case of using in a high temperature environment without almost retaining an internal strain in a method for manufacturing the article of the resin. SOLUTION: A molten thermoplastic resin 2 is fed only by an extrusion force from a long land die 1 while expediting to cool the resin 2 through the die 1 by an extrusion force from an extruder. In the case of extruding, the die 1 is forcibly cooled. Thus, the lengthy article can be manufactured, a take- off unit is unnecessary, and a lengthy article manufacturing line can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a long thermoplastic resin.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a long product of a thermoplastic resin, as shown in FIG. 3, a thermoplastic resin a is extruded from a die b (die) and the extruded resin a is drawn. There has been known a method of pulling and sizing while adjusting the take-off speed with an external take-off machine. Further, as a method of extruding a material by an extruder to produce a long product without giving a substantial tensile force, a method of producing a rubber mandrel disclosed in JP-A-61-102220 has been known. The method involves passing the rubber compound through a heated metal tube for surface vulcanization with just a pushing force immediately after extruding the rubber compound from the extruder, and then passing the mixture through a pressure tube, vulcanizing can, etc. to advance vulcanization. there were.

[0003]

However, in the method described with reference to FIG. 3, since the resin immediately after being extruded from the base b is soft, it is necessary to adjust the take-up speed so that the shape does not change. However, it is difficult to adjust the take-off speed so that the outer diameter c of the resin in the base b is equal to the outer diameter d of the resin coming out of the base b. Also, the outer diameter d becomes larger and undulation occurs on the outer peripheral surface, resulting in a defective product. Therefore, the tensile force acts in the longitudinal direction on the resin so that the outer diameter d becomes smaller than the outer diameter c. In addition, the take-up speed was adjusted to be relatively large.

As a result, the resin is solidified in a state where a tensile force acts in the longitudinal direction, so that internal strain in the longitudinal direction remains in the completed elongated product. There is a problem that the long object becomes short due to the residual internal stress which is about to be compressed in the direction, and the outer diameter becomes large accordingly.

[0005] Further, since the mandrel is used for producing a rubber hose, it is preferable that the mandrel be excellent in flexibility. It is better not to crosslink resin mandrel (because it is excellent in flexibility)
Although preferable, such a non-crosslinked type resin mandrel cannot be produced by the production method of JP-A-61-102220. In JP-A-61-102220, the vulcanization proceeds by passing the rubber compound through a heated metal tube, a pressure tube, a vulcanization can, etc. in order from the upstream side, so that a thermoplastic resin can be used as a material. Did not.

Accordingly, the present invention solves the above-mentioned problems and hardly causes any residual internal strain. Even when used in a high-temperature environment, it is possible to manufacture a thermoplastic resin having a very small change in outer diameter. It is an object of the present invention to provide a method for producing a long resin product.

[0007]

In order to achieve the above-mentioned object, a method for producing a long-sized thermoplastic resin according to the present invention comprises the steps of: And only the pushing force is sent out from the long die while promoting cooling. At this time, the long ground die is forcibly cooled.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing embodiments.

In FIG. 1, reference numeral 1 denotes a long land die (LLD) which is connected to a discharge port of an extruder (not shown) and has a longitudinal circular hole 7; 2 is a thermoplastic resin; Is a cooling means for forcibly cooling the cooling medium.
Here, the long ground die 1 refers to a long land die for sizing a molded product. The length of the long gland die may be such that the long object of the thermoplastic resin can be cooled (although there is no particular limitation) so as to maintain its shape, and varies depending on the outer diameter of the long object. ~Ten
m, preferably about 1 to 5 m.

[0010] Thus, the molten thermoplastic resin 2 is passed through the long gland die 1 with the pushing force from the extruder to promote cooling. In other words, the long ground die 1 is cooled by the cooling means 3.
Is extruded while forcibly cooling.

More specifically, on the upstream side 5 (ie, the extruder side) of the long gland die 1, the thermoplastic resin 2 is in a molten state, and becomes gradually harder as it proceeds to the downstream side 6. Then, the thermoplastic resin 2 is cooled and solidified in the long land die 1 to such an extent that the cross-sectional shape does not change. In addition, as the cooling means 3,
For example, a device configured to circulate water around the long ground die 1 or a device that blows air are used, but other devices may be used.

Further, the thermoplastic resin 2 is sent out from the long land die 1 with only a pushing force. This allows
The thermoplastic resin 2 is sized by the long die 1 with only the pushing force. That is, the outer diameter D of the long object 4 to be manufactured is determined by the inner diameter E of the circular hole 7 of the long gland die 1.

Subsequently, the thermoplastic resin 2 is fed only by the above-mentioned pressing force to be completely solidified. Thereby, the long object 4 is obtained. It is preferable that a cooling means (not shown) for cooling with water or air is provided on the downstream side to forcibly cool and completely solidify the thermoplastic resin 2.

Thereafter, the long object 4 is cut into a predetermined length by a cutting machine (not shown), thereby forming a circular mandrel 8 having a constant outer diameter D and a circular cross section as shown in FIG.

However, according to this method for producing a long thermoplastic resin, the external force in the longitudinal direction hardly acts from the start of the solidification of the thermoplastic resin 2 to the complete solidification thereof (particularly in the longitudinal direction). Hardly acts on the long object 4), so that the internal strain hardly remains in the long object 4 (the internal stress hardly remains). Moreover, a long-sized object 4 having a uniform diameter according to a desired outer diameter can be formed without a change in shape such as undulation on the outer peripheral surface. When the long object 4 is used as a mandrel 8 for manufacturing a hose, there is almost no residual internal distortion. Therefore, even when used at a high temperature, the change in the outer diameter of the long object 4 is extremely small (the diameter is almost increased). Absent).

Thus, when the long object 4 is the mandrel 8, a hose having a stable inner diameter can be manufactured. In addition, since the diameter is hardly increased, the life of the mandrel is remarkably prolonged, the mandrel can be used many times, and the manufacturing cost of the hose can be reduced. Also, a take-up machine is not required.

[0017]

EXAMPLE Next, the mandrels (long objects) of Examples 1 and 2 were actually manufactured by the method of manufacturing a long object described with reference to FIGS. Then, heat tests were performed on the mandrels of Examples 1 and 2 and Conventional Examples 1 and 2. The materials of Examples 1 and 2 and Conventional Examples 1 and 2 were polymethylpentene, and the length of each mandrel was 400 mm. In the heat test, 10 cycles of heating at 150 ° C. for 1 hour and cooling for 1 hour with normal temperature water as one cycle were performed with the mandrel suspended in the gear oven. The length and outer diameter of the mandrel were measured at the initial stage and at the second, fourth, sixth, eighth, and tenth measurements. The measurement of the outer diameter was performed at a total of three places: the middle part and both ends of the mandrel.

Table 1 below shows the measured values of the length of the mandrel, and FIG. 4 is a graph showing the shrinkage change rate in each cycle. The shrinkage change rate was calculated by the formula (400−x) ÷ 400 × 100, where x is the measured value of the length dimension.

[0019]

[Table 1]

Tables 2 and 3 show the minimum, maximum, and average values of the outer diameter of each mandrel, and the flatness of the mandrel. FIG. 5 shows the outer diameter change rate in each cycle. FIG. The outer diameter change rate was calculated by the following equation, where the average value of the outer diameter in the initial stage was y, and the average value of the outer diameter in each cycle was z: (zy) ÷ y × 100.

[0021]

[Table 2]

[0022]

[Table 3]

As is apparent from FIG. 4, the shrinkage change rates of the first and second embodiments are significantly smaller than those of the first and second conventional examples. That is, Examples 1 and 2 were difficult to shrink in the longitudinal direction. Also, as is apparent from FIG. 5, the outer diameter change rates of Examples 1 and 2 are significantly smaller than those of Conventional Examples 1 and 2. That is, Example 1,
In No. 2, the outer diameter was not easily increased even after heating to 150 ° C. Further, as is clear from Tables 2 and 3, Examples 1 and 2 have significantly smaller flatness than Conventional Examples 1 and 2, and can be said to have a cross-sectional shape close to a perfect circle.

Further, when rubber hoses were actually manufactured using the mandrels of Examples 1 and 2 and Conventional Examples 1 and 2,
While Examples 1 and 2 could be used repeatedly more than 60 times, Conventional Examples 1 and 2 increased their outer diameter after 10 uses and could not be used any more.

[0025]

Since the present invention is configured as described above, the following effects can be obtained.

According to the method for producing a long thermoplastic resin according to the first aspect, internal strain hardly remains, and dimensional change is extremely small even when used in a high temperature environment (external diameter change is extremely small). ) A long product 4 of a thermoplastic resin can be manufactured. Furthermore, a take-up machine is not required, and the line for manufacturing long products can be shortened. If the manufactured long object 4 is used as a mandrel for manufacturing a rubber hose, a rubber hose having a stable inner diameter can be manufactured. In addition, the life of the mandrel is significantly prolonged, and the manufacturing cost of the hose can be reduced.

According to the method for manufacturing a long-sized thermoplastic resin according to the second aspect, the thermoplastic resin 2 is formed in the long land die 1.
Can be efficiently cooled, and the thermoplastic resin 2 can be reliably sized only by the pushing force (without giving a tensile force).

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view of a mandrel.

FIG. 3 is an explanatory view of a conventional example.

FIG. 4 is a graph.

FIG. 5 is a graph.

[Explanation of symbols]

 1 Long ground die 2 Thermoplastic resin

Claims (2)

[Claims] 1. A thermoplastic resin characterized in that the molten thermoplastic resin 2 is sent out from the long-ground die 1 only with the above-mentioned pressing force while cooling is promoted through a long-land die 1 with an extrusion force from an extruder. Manufacturing of long objects. 2. The method according to claim 1, wherein the long land die 1 is forcibly cooled.