JPH0438575B2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> The present invention relates to a method for producing a tube having a pattern on its outer surface suitable for synthetic resin tube containers used in a wide range of fields such as cosmetics, foods, and pharmaceuticals. This relates to manufacturing equipment.

<<Prior Art>> Synthetic resin tubes commonly used in tube containers are formed by extrusion molding to form a cylindrical body, and then the outer surface of the body is printed or hot-stamped as desired. A pattern is added. However, such decoration through secondary processing not only increases the number of manufacturing processes and causes an increase in costs, but also makes it impossible or extremely difficult to express three-dimensional patterns, resulting in a monotonous design. The appearance of the tube container is made to be less variable. In addition, when molding a body part, it is a well-known technique to mold a part of the peripheral wall with a resin of a different color tone from the other parts over the entire wall thickness, but it is also known that It has still not been possible to form the annular body into a smooth annular body with no irregularities on the inner surface while protruding in a convex shape. Therefore,
For products such as tube containers whose bottoms are crushed and sealed, it was considered impossible to create three-dimensional patterns through extrusion molding.

《Problems to be Solved by the Invention》 The present invention has been made in view of the above-mentioned circumstances, and its purpose is to form a three-dimensional pattern on the outer surface of the body at the same time as molding the body in a reliable and relatively simple manner. It is an object of the present invention to provide a method and apparatus for manufacturing a synthetic resin tube suitable for a synthetic resin tube container formed in.

<Means for Solving the Problems> In order to achieve the above object, according to the method of the present invention, a cylindrical flow path portion is defined between a core mold and an outer mold attached around the core mold. The diameter of the flow path portion gradually decreases from the proximal end toward the distal end, and the molten first thermoplastic synthetic resin from the main extrusion molding machine is allowed to flow into the flow path portion from the base end. On the other hand, a sprue communicating with an auxiliary extrusion molding machine is locally opened in the middle of the flow path, and a second thermoplastic synthetic resin having compatibility with the first resin is supplied from the sprue to the first resin. The first resin and the second resin are extruded from the tip side to the outside without mixing, and then cooled while regulating the inner diameter of the extruded resin. A cylindrical body is formed using the first resin, and at the same time, a convex band pattern is integrally formed on the outer surface of the body using the second resin.

Furthermore, the apparatus of the present invention for carrying out the above method includes:
An outer mold is attached around the core mold, a cylindrical flow path portion whose diameter gradually becomes smaller toward the tip is defined between the outer surface of the core mold and the inner surface of the outer mold, and the base of the flow path portion is formed. A main extruder that communicates with a sprue opened at an end to provide a molten first synthetic resin into the flow path, and one or more sprues that are locally opened in the middle of the flow path. Attaching to each of the outer molds one or more auxiliary extrusion molding machines that provide a belt-like molten second synthetic resin to the outside of the first resin flowing down in the flow path in communication with the outer mold; A cooling section is provided that cools the resin extruded into a cylindrical shape from the tip of the channel section while regulating the inner diameter to form a body section having a predetermined inner diameter.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a tube manufactured according to the present invention;
In other words, it shows a tube container using a body,
In the figure, reference numeral 1 denotes a substantially cylindrical body formed by extrusion molding from a synthetic resin, and a spout hole 3 is bored in the upper end of this body 1. A neck portion 2 to which a cap (not shown) is screwed is welded via a shoulder portion 4, and a bottom portion 5 of the body portion 1 is flattened and sealed by means such as heat welding. As clearly shown in FIG.
-7 is integrally formed in the axial direction of the body. These band patterns are preferably formed from a resin of a different color tone from the rest of the body 1, and are molded at the same time as the body 1, which will be described later. On the other hand, the inner surface of the body 1 has a smooth circular shape, and the band patterns 6 and 7 do not reach this inner surface, so that the resin exposed on the inner surface is completely homogeneous.

As can be understood from the above, in this tube container, the convex band patterns 6 and 7 give a remarkable change to the appearance of the body 1, giving a completely different impression from conventional decorations. It has become a thing. This effect can be further enhanced by making the resin forming the band patterns 6 and 7 different in color from the other parts, and since they are molded without any troublesome secondary processing, the cost can be reduced. It also has some merits. Furthermore, since the inner surface of the body 1 is completely smooth and homogeneous, there is no risk of punctures or poor sealing of the bottom 5.

Next, FIG. 3 shows an apparatus according to the present invention used for manufacturing the above-mentioned tube.
and an outer mold 12 attached around the core mold, and between the outer surface of the core mold 10 and the inner surface of the outer mold 12, a space with a circular cross section forming a flow path portion 13 is defined. has been done. The core mold 10 is formed to gradually become smaller in diameter toward the tip, and along with this, the flow path portion 13
The cross-sectional area becomes smaller toward the tip (downstream side). The outer mold 12 consists of a die body 12a, a first die chip 12b, and a second die chip 12c, which are arranged in this order in close contact with each other from the base end side to the distal end side of the core mold 10, and are arranged in a direction from the base end side to the distal end side of the core mold 10. The portion 13 terminates at an extrusion port 14 on the distal end surface of the second die chip 12c.

A main extrusion molding machine 15 is attached to the die body 12a of the outer mold 12, and the tip of this molding machine 15 passes through a runner 16 bored in the die body 12a.
It communicates with a first sprue 17 that is annularly opened at the base end of the flow path section 13 . On the other hand, a first auxiliary extrusion molding machine 18 is attached to the first die chip 12b, and the tip thereof communicates with a second sprue 20 that is opened in the middle of the flow path section 13 via a runner 19. A second auxiliary extrusion molding machine 21 is attached to the second die tip 12c, and its tip is a third auxiliary extruder 21 that opens further downstream than the second sprue 20 of the flow path section 13 via a runner 22. It communicates with sprue 23. These auxiliary extruders 18 and 21
The runners 19 and 22 are attached to each other with a 90° offset from each other, and as shown in FIGS.
a and 22a, and both ends of each branch part are locally opened to the flow path part 13.
0 and 23-23, respectively. Therefore, the second sprue 20-20 and the third sprue 23-23 are located at positions offset from each other by 90 degrees with respect to the center, and the sprues of each pair are located at symmetrical positions. still,
At the positions where these sprues open, the cross-sectional area of the channel portion 13 is slightly and temporarily reduced by providing recesses 24-24 on the outer surface of the core mold 10 at those locations, as shown in FIG. It is preferable to increase it to .

The tip 10a of the core mold 10 is formed into a small diameter cylindrical shape and extends forward beyond the extrusion port 14 of the second die tip 12c, and the outer diameter of the tip 10a is adjusted to the desired inner diameter of the body 1. and set it. As will be described later, this tip 10a plays a role as a cooling section, and the pipe 11 that has passed through the center of the core mold 10 opens within the tip 10a to circulate cooling water. The member indicated by the reference numeral 25 in the figure is a roll for taking off the molded product.

The method for manufacturing the body 1 as shown in FIG. 2 using the apparatus having the above-mentioned configuration will be explained below. First, the first thermoplastic resin 26 is melted from the main extrusion molding machine 15. The first resin is caused to flow into the flow path section 13 and flow down. As described above, the cross-sectional area of the flow path portion 13 decreases toward the tip, so the flow velocity of the resin 26 increases as it goes downstream, and the pressure becomes higher downstream due to the viscosity of the resin itself. Next, the first resin 26
While continuing to flow the second thermoplastic synthetic resin 2 from the first and second auxiliary extruders 18 and 21.
7 and 27a respectively in a molten state into the flow path section 13, the second and third sprues 20
-20 and 23-23 are locally opened, so the second resin is added in a band shape to the outside of the first resin flowing down the flow path section 13.
The pressure in the added portion becomes higher than that in the other portions. However, in the flow path section 13, the flow is faster and the pressure is higher on the downstream side, so uniform diffusion of pressure is inhibited, and the second resins 27, 27
A is extruded from the extrusion port 14 into the atmosphere together with the first resin 26 without being mixed with the first resin 26 and remains in a band shape. Then, the extruded resin is suddenly released from its high pressure state, so it expands and increases in wall thickness, but at this time, the part where the second resin is added is under even higher pressure than other parts. Because it is located at the bottom, the expansion rate is higher than other parts, and the wall thickness also increases. This condition is illustrated in FIG. 6, where the portion to which the second resin has been added protrudes more than the other portions in both the outward and inward directions. After that,
By bringing the inner surface of the extruded resin into a sleeve into close contact with the outer surface of the cooling part (core-shaped tip) 10a and cooling while regulating the inner diameter of the sleeve, only the second resin on the outside protrudes in the form of a band. A molded product 28 having a predetermined inner diameter is obtained (see FIG. 7). After this molded product 28 is taken up by a roll 25, the body portion 1 is formed by cutting it into a predetermined length, and the outer protruding portions form band patterns 6-6 and 7-7.

Note that the first resin 26 and the second resin 27, 27a
Although it is necessary for the second resin to be compatible, it is preferable that the second resin has a different color tone from that of the first resin. It may also be used as a resin. Of course, the second resins 27 and 27a can have different colors. In addition, as shown in the figure, a flow path section 13 in which sprues 20 and 23 are opened is also provided.
If the recess 24 is provided in this part, the first
Because the pressure of the resin 26 in the second
The resins 27, 27a do not spread in the circumferential direction and form a clearer band pattern.

When the height (thickness) of the band patterns 6 and 7 of the body 1 formed using the above-described method and apparatus was measured, it was approximately 20 to 25% of the wall thickness of the body. If it is desired to increase this thickness, that is, to further enhance the three-dimensional effect of the band patterns 6 and 7, the cross-sectional shape of the channel portion 13 may be changed as shown in FIG. 8 or 9. I can do it. That is, in the embodiment shown in FIG. 8, the second sprue 20-
On the downstream side of the third sprue 23-23, there is a groove 30-30 having a width approximately equal to the width of the sprue, and on the downstream side of the third sprue 23-23, there is a groove 31-3 having a width approximately equal to the width of the sprue.
1 are formed in the axial direction up to the extrusion port 14, and in the embodiment shown in FIG. 9, similar grooves 40-40 and 41-41 are formed on the inner surface of the outer mold 12. In the case of the former example (FIG. 8), the wall thickness of the part where the second resin 27, 27a is added is greater in the inner part than in the other part, and therefore the atmosphere is removed from the extrusion port 14. The expansion rate when released inside increases, and the inner diameter is regulated by the cooling section 10a, so that all of this expansion portion expands outward, so the thickness of the band patterns 6 and 7 increases. That's what I do. In this case, the second resin 27, 2
The amount of 7a can be greater than in the previous example. It is also clearer that the embodiment of FIG. 9 allows the thickness of the band patterns 6, 7 to be increased. As a result of experiments, it was confirmed that in accordance with these Examples, the thickness of the band pattern could be made approximately 2 to 3 times that of the above-mentioned Examples.

In the embodiment described above, two pairs of band patterns 6-6 and 7-7 are formed on the outer surface of the body 1, but the number and positional relationship of the band patterns are not limited to this. Of course, it can be changed arbitrarily.
Further, the shape of the body portion 1 can also be various other than a cylindrical shape.

<<Effects>> As described above, in the method for manufacturing a synthetic resin tube according to the present invention, a cylindrical flow path portion is defined between a core mold and an outer mold attached around the core mold, and the flow path portion is The diameter of the channel gradually decreases from the proximal end to the distal end, and the molten first fluid from the main extruder is inserted into the channel.
A thermoplastic synthetic resin is allowed to flow in from the base end side, while a sprue communicating with an auxiliary extrusion molding machine is locally opened in the middle of the flow path, and the resin is compatible with the first resin through the sprue. A second thermoplastic synthetic resin is caused to flow into the outside of the first resin in a band shape, extruded from the tip side to the outside without mixing the first resin and the second resin, and then extruded. By cooling the resin while regulating its inner diameter, the first
The cylindrical body is molded using the second resin, and at the same time, the convex band pattern is integrally molded on the outer surface of the body using the second resin, thereby ensuring that the three-dimensional pattern is formed. Moreover, it can be formed without secondary processing.

Furthermore, the device according to the present invention for carrying out the above method includes attaching an outer mold around the core mold, and having a diameter gradually decreasing toward the tip between the outer surface of the core mold and the inner surface of the outer mold. a main extrusion molding machine defining a cylindrical flow path and communicating with a sprue opened at the proximal end of the flow path to provide a molten first synthetic resin into the flow path; Providing a molten second synthetic resin in a band shape on the outside of the first resin flowing down in the flow path by communicating with one or more sprues locally opened in the middle of the flow path 1 One or more auxiliary extrusion molding machines are attached to each of the outer molds, and the resin extruded into a cylindrical shape from the tip of the channel is cooled while regulating the inner diameter to form a body with a predetermined inner diameter. Since it was decided to provide a section, it is relatively simple and can be manufactured efficiently.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a synthetic resin tube container formed using a tube manufactured by the method of the present invention, FIG. 2 is a perspective view of the body of the container, and FIG.
The figure is a cross-sectional view showing an apparatus according to an embodiment of the present invention for manufacturing the container, FIG. 4 is a cross-sectional view taken along the line AA in FIG. 3, and FIG. 5 is a cross-sectional view taken along the line B-B in FIG. ,
Figure 6A is an enlarged sectional view for explaining the state of the extruded resin, Figure 6B is a sectional view showing the state of the resin before cooling, Figure 7 is a sectional view after cooling, Figures 8 and 6. FIG. 9 is a sectional view showing another embodiment of the manufacturing apparatus according to the present invention. 1...Torso, 2...Neck, 5...Bottom, 6,7
... Band pattern, 10 ... Core type, 10a ... Cooling part,
12... Outer mold, 13... Channel section, 15... Main extrusion molding machine, 17, 20, 23... Sprue, 18, 21
... Auxiliary extrusion molding machine, 26 ... First thermoplastic synthetic resin, 27, 27a ... Second thermoplastic synthetic resin, 30, 31, 40, 41 ... Concave groove.

Claims (1)

[Claims] 1. A cylindrical flow path is defined between a core mold and an outer mold attached around the core mold, and the flow path is gradually drawn from the proximal end to the distal end. The molten first thermoplastic synthetic resin from the main extruder is allowed to flow into the flow path from the proximal end side, while a sprue communicating with the auxiliary extruder is provided in the middle of the flow path. A second thermoplastic synthetic resin having compatibility with the first resin is locally opened through the sprue and flows in a band shape outside the first resin, and the first resin and the second resin are By extruding the extruded resin from the tip side to the outside without mixing it with the resin, and then cooling the extruded resin while regulating its inner diameter, a cylindrical body is formed with the first resin and at the same time. A method for manufacturing a synthetic resin tube, comprising integrally molding a convex band pattern on the outer surface of the body using the second resin. 2. An outer mold is attached around the core mold, and a cylindrical flow path portion whose diameter gradually becomes smaller toward the tip is defined between the outer surface of the core mold and the inner surface of the outer mold. a main extruder that communicates with a sprue opened at the proximal end and provides a molten first synthetic resin into the flow path; and one or more extruders that are locally opened in the middle of the flow path. The first tube communicates with the sprue and flows down inside the flow path.
one or more auxiliary extruders that provide a strip of molten second synthetic resin on the outside of the resin;
A composition characterized in that a cooling section is installed on each of the outer molds and cools the resin extruded into a cylindrical shape from the tip of the flow path section while regulating the inner diameter to form a body section with a predetermined inner diameter. Equipment for manufacturing resin tubes. 3. Claim 2, characterized in that a concave groove having a width substantially equal to the width of the sprue is formed on the outer surface of the core mold on the downstream side of the sprue that communicates with the auxiliary extrusion molding machine. Equipment for manufacturing synthetic resin tubes. 4. Claim 2, characterized in that a concave groove having a width substantially equal to the width of the sprue is formed on the inner surface of the outer mold on the downstream side of the sprue that communicates with the auxiliary extrusion molding machine. Equipment for manufacturing synthetic resin tubes.