JPH039822A - Method for molding and bonding head part of squeeze tube container - Google Patents

Abstract

PURPOSE:To make a strong bonding of a head part with a cylinder part and prevent resin from overflowing to the inner surface of a cylinder by a structure wherein an injected resin layer, which is formed on the inside surface of the upper end part of the cylinder part, is made to be thicker than its upper part (below the upper end part) and, further, the upper end part is bent inwards at the mold clamping process, when a head part is injection-molded at the upper end part of the cylinder part so as to be bonded with the cylinder part. CONSTITUTION:A cylinder part 2 is coveringly installed onto a first male mold 12. Further, an annular notched part 22 is provided at the lower peripheral edge part of a truncated conical part 25, which corresponds to the shoulder of a container. By raising a male mold 26 and an actuating pipe 20, the upper end part 28 of a cylinder is bent inwards along the inner surface of a shoulder mold 16 so as to be faced against the notched part of the first male mold 12 and to position the tip 8 of the bent upper end part 28 of the cylinder lower than the upper end 29 inside of the notched part 22 opposite to it under the state that the upper end of the actuating pipe 20 abuts against the under surface of the shoulder mold 16. A space, to which molten resin is injected, is increased by providing the notched part 22, resulting in easily going round molten resin peripherally.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a method for forming and joining the head of a squeeze tube container,
More specifically, the present invention relates to an improvement in a method of molding and joining a mouth and neck part and a shoulder part (hereinafter referred to as the head part) by an injection molding method to one end of a body manufactured by an extrusion molding method or the like.

(Prior Art) Squeeze tube containers are often used for kneaded polishes, jelly-like cosmetics, and other viscous products because they allow easy removal of only the appropriate amount to be used.

In order to manufacture such a squeeze tube container, usually a male mold is provided with a truncated cone corresponding to the xr7 portion of the container and a protruding portion corresponding to the mouth and neck of the container on the upper part thereof, and the male mold. a female mold which cooperates with the container head to form the container head and joins the head to the body (the female mold generally has an inner surface parallel to the crest of the male mold); is used. That is, first, the sleeve-shaped body is produced by a known extrusion molding method, cut to a desired length, and then glued together.The male and female molds are then assembled and clamped, and the male and female molds are assembled. The head (becoming 11S) is placed in the injection space formed between
Inject the molten resin using the upper part of the inlet as the gate position.
Inject for a few seconds. ), and the head is formed in a structure in which the lower part of the head (specifically, the shoulder) overlaps one end of the body, and at the same time forms a joint between the head and the body. In addition,
The molten resin is cooled, then the mold is opened and the product (container) is released.
will be taken out.

At this time, the overall thickness of the joint is usually the same as the thickness of the shoulder outside the joint. In other words, an injection space with a constant thickness is formed between the male mold and the female mold,
The thickness of the injected resin layer at the joint part is equal to (total thickness of the joint part - thickness of the body part).

(Problems to be Solved by the Invention) When the head and body of the container are joined using the above-mentioned conventional technique, the following problems occur.

(1) The resin injected from the upper gate position of the head (which will become the part) flows downward through the injection space while being cooled from the gate position along the outer surface of the male mold. Instead of flowing uniformly over the entire surface of the product, it flows around the circumference in a vertical band shape, so the product always has a merging line called a "weld line" from above the head. It forms all the way down.

]ni L, T, in the upper part of this weld line near the gate position, the resin temperature does not drop much due to the mold, and it is formed at the initial stage of injection, so it is difficult to bond the weld line below the head. Although the strength is strong, the temperature of the resin is lowered by the mold before it reaches the tip of the body (in other words, the lowest part of the injection space), and the weld line below the head formed at the end of injection has a lower adhesive strength. becomes lower. Furthermore, even if the head and body are made of the same material, insufficient welding will occur at the joint, which may cause the joint to peel or crack at the lowest portion.

(2) In order to eliminate the insufficient bonding and cracking shown in (1), the temperature of the molten resin is raised and the injection pressure is increased, but if the molten resin temperature is too high, the tip of the body becomes softer than necessary. Not only does this lead to deformation due to heat dissipation, and it takes a long time to cool down, which impairs production efficiency, but also causes sink marks due to delayed solidification of the internal resin, resulting in poor appearance. on the other hand,
If the injection pressure is too high, the head forming material will not protrude to the inside surface of the body other than the joint, which will not only worsen the appearance, but also cause problems when decorating the outside surface of the body by printing, painting, etc.
There is a problem in that it cannot be installed accurately on the mandrel (iron core), resulting in misaligned printing and poor coating.

Therefore, it is not possible to consistently produce good products by increasing the temperature of the molten resin or increasing the injection pressure.

(Means for solving the problem) The present invention solves these problems! ), and its structure is as follows.

A male mold (26) having a truncated cone (25) at the top and a female mold (1) having an inner surface (27) substantially parallel to said cone.
5) into the mold open state, and insert the sleeve-shaped body part (2) into the male mold.
), a mold clamping process of forming an injection space (21) with the male and female molds, an injection process of injecting molten resin into the injection space, and a cooling process of cooling the molten resin. In a method for forming and joining a squeeze tube container (1) in which the head (3) and the joint (6) between the body and the head are formed at the same time, the male mold described in 1iij includes a truncated conical part A male mold having an annular cutout (22) with a depth equal to or greater than the thickness of the container body plate is used at the lower peripheral edge of the male mold, and in the mounting step, the sleeve-shaped body tip (8) is attached to the truncated cone of the male mold. located above the lower end, and in the mold clamping step described in 1iij, the upper end of the body (28)
is bent along the inner surface of the female mold so as to face the cut out part (22) of the male mold, and the tip (8) of the body part is set higher than the upper end (29) of the opposing cut out part (22). A method for forming and joining the head of a squeeze tube container, characterized by forming an injection space at the bottom.

(Function) The head forming/joining method of the present invention involves bringing the head inside the upper end of the squeezable body manufactured by extrusion molding or laminating, and forming the head by injection molding. However, when joining at the same time, the thickness of the injection resin layer formed on the inside part of the upper end of the body at the joint part is made thicker than the upper part, and in this thick part, the resin layer flows in a band shape from the gate position. The 41-inch structure allows the molten resin to flow around in the left and right circumferential direction, and does not impair the fluidity of the resin to fill the filling state, so the resin temperature can be lowered until the weld line is completely formed. The head can be firmly joined to the tip of the body without increasing the resin temperature or injection pressure more than before, and the welding strength of the weld line at the lowest point can be increased. . In addition, in the mold clamping process, the upper end of the body is bent inward so that it faces the cut-out part of the male mold, thereby forming an injection space at the joint. This makes it easier to secure a space for the sequentially flowing molten resin to rise along the inner surface of the upper end of the body, and at the same time makes it easier to discharge air out of the injection space, thereby preventing the resin from spilling out onto the inner surface of the body. .

(Example 1) Hereinafter, an example of the present invention will be described with reference to the drawings (Fig. 1.2).

Figure 1 shows the squeeze tube container (
Fig. 2 is a structural diagram of a mold showing the manufacturing process of the squeeze tube. b): A sectional view showing the mold clamped state in which the female mold is assembled; (C): A sectional view showing the state in which the female mold is removed upward after the mold is clamped and the head molding material is injected and cooled.

The squeeze tube container l of this example is made by integrally bonding a head 3 molded by injection molding to the tip of a sleeve-shaped body 2 manufactured by extrusion molding, and the joint 6 is thick. .

In the container H'-, the body 2 has a diameter of 3 (1 m/m, wall thickness 0.
45a/a is made of low-density polyethylene, and the head 3 joined to the body is also made of the same material, low-density polyethylene. An opening 10 that communicates with the inside of the body 2 is formed by a mouth 9 at the upper end of the mouth and neck 4 that forms part of the head 3;
A male thread is formed on the outer surface of the mouth and neck portion 4, and the outer and inner surfaces of the truncated conical shoulder portion 5 are inclined at 30 degrees, and the wall thickness is 1 m/11.
1 is .

The thick portion 7 located inside the body tip 8 is formed to have a thickness of 2.3 m/m including the body tip 8. Further, the body tip 8 is bent toward the mouth and neck side and is formed in an annular shape with a width of 2 m/m, and the inner thick portion 7 is formed with a width of V 2 m/m. Note that, as shown in FIG. 2(C), there is a continuous portion above the mouth portion 9 with the mouth:1<extension portion II, which is cut and discarded after molding.

Next, the manufacturing process of the above-mentioned container will be explained.

First, talking about the molds, the male mold 26 consists of a first male mold 12 and a second male mold 13 (14 is the base) that form the inner surface of the head 3, and a female mold that forms the outer surface. is indicated by 15. The male mold is made by combining a second male mold 13 into a first male mold 12 and connecting them to a base 14. A passage (not shown) for compressed air is formed in the base 14, and the second male mold 13 is configured to slide up and down by blowing out the air. On the other hand, the female mold 15 is composed of a shoulder mold 16, a screw mold 17, and a nozzle mold 18, which are housed in a holder 19.
A screw type that is linked to the vertical movement of 0 and is a split type due to this movement! 7 is for closing the mold or opening the mold outward. More specifically, the shoulder type 16 is a boulder type.
19, the screw mold I7 moves downward to open the mold outward, and moves upward to close the mold toward the axis. The mold cooling water flows through the holder I9 (not shown), the molding operation pipe 20 moves upward, maintains the injection space 2I formed by the male mold 2G and the female mold 15, and Perform 17 mold clamping,
It also moves downward and opens the female mold 15.

The outer diameter of the first male mold 12 is such that the body 2 can be mounted thereon, and the upper surface corresponding to the shoulder 5 of the container forms a truncated conical part 25 formed at an angle of 30 degrees. At its lower peripheral portion, an annular cutout 22 with a width of approximately 2 am and a depth of 0 (45 mm) is provided.

The second male mold 13 has a lower upper surface formed at an angle of 30 degrees, similar to the outer surface of the conical portion of the first male mold, so that when assembled, it is flush with the upper surface of the first male mold 12, The upper part stands vertically to form the logger 1 part 4 of the container. In addition, female type I
5 is an inner surface 2 substantially parallel to the male frustum 25;
7.

Next, the head 3 is formed using the above mold structure, and at the same time the body 2 is formed.
We will explain how to join.

The male mold 26 and the female mold 15 are opened, and the sleeve-shaped body part 2 is attached to the first male mold 12, and its tip 8 M 2 mm is "2" larger than the inclined lower end of the conical part of the first male mold I2. Attach it so that it protrudes toward the side (Figure 2 (a)).

Next, after moving the male mold 26 to a position directly below the female mold I5, the male mold 26 and the operating pipe 20 are raised, and the upper end portion 28 of the body is bent toward the mouth and neck portion 4 side along the inner surface of the shoulder mold IG. Then, when the upper end of the actuating pipe 20 is brought into contact with the lower surface of the shoulder mold 1G, the tip 8 of the bent upper end 28 of the body is brought into contact with the cut-out portion 22 of the first male mold 12. Mouth and neck: Positioned below the upper end 29 on the π≦4 side.

Thereafter, by slightly raising the operating pipe 20 along with the male mold to the sky, the screw mold I is inserted through the shoulder mold 16.
7 toward the axis. When the screw mold I7 comes into close contact with the lower surface of the nozzle mold 18, the raising of the operating pipe 20 is stopped to maintain the clamping state of each female mold, and at the same time, the raising of the male mold is stopped, so that the injection space 21 is closed. form (Fig. 2 (bno).

In this state, the nozzle tadge part 23 and the gate part 24 are used as passages, and the resin temperature is 200°C and the injection pressure is 45°C, as in the conventional method.
The molten resin (polyethylene is used in this example) is flowed into the injection space 21 at a rate of Kg/cod'.

The injected resin passes through the mouth and neck part 4 and reaches the shoulder part 5, where it flows in the form of a single line, and flows in the left and right circumferential direction along the upper surfaces (30 degree slope) of the second male mold 13 and the first male mold 12. When the tip of the flowing resin reaches the cutout part 22 located at the bottom of the injection space 21, the speed at which the molten resin spreads in the left and right circumferential direction increases, and furthermore, it rises toward the inner surface of the shoulder mold 1G. Since the molten resin flows, the tips of the molten resin are merged in the circumferential direction and a weld line is formed before the molten resin temperature decreases due to the mold, that is, while the molten resin temperature necessary for strong welding is maintained. can be formed.

After injecting the tCg molten resin, after cooling for several seconds, the male molds 12, 13. The screw mold 17 opens. At this time, the body having the head 3 remains attached to the first male mold I3. Next, compressed air is communicated to the first male mold 12 to open the second male mold 13. is slightly raised to create a space between the first male mold 12 and the second male mold 13, forming a passage for compressed air, and blowing it out to the inner surface of the head 3, the first male mold I2. The tube container l is discharged upward. Next, the tube container l is placed between the mouth and neck;
An opening 10 is formed by cutting above the hole of 1-4.

A comparison of the tube container manufactured by the method of the present invention (a) and the tube container manufactured by the conventional method (b) is as shown in the following table.

As shown in the table above, the tube container of this example has improved joint strength compared to the conventional product without increasing the resin temperature and pressure during injection more than necessary, and the inner surface of the body It can be seen that there is no inflow of resin into. In other words, since the resin flows in the left and right circumferential directions while the resin temperature does not drop, the bonding strength of the weld line is high, and when the cap is tightly tightened on the threaded part or the shoulder part 5 is bent to squeeze out the contents. No cracks will occur at the weld line.

The reason why a weld line is formed before the resin temperature drops is as follows: (i) By providing the cutout portion 22, the injection space for the molten resin increases, flow resistance is reduced, and the molten resin wraps around in the circumferential direction. (11) A large amount of resin can flow into the cutout part 22, and there is also a flow of molten resin that causes the resin to rise toward the inner surface of the shoulder mold 16 due to the reaction of the cutout part 22 going down one step. , the injection space may become warm in a short period of time.

Also, the reason why there is no inflow (protrusion) of resin into the inner surface of the body other than the injection space is that when forming the injection space in the mold clamping process, the upper end 28 of the body is bent along the inner surface 27 of the female mold. By facing the cutout part 22 of the male mold and positioning the tip 8 below the upper end 29 of the opposing cutout part 22 to form the injection space of the joint part, a gentle inclination angle can be achieved as in the conventional case. Unlike the case where the molten resin flows directly down to the inner surface of the tip of the body, the molten resin flows down one step on the neck side of the body tip 8 and reaches the inner surface of the tip of the body, so the newly flowing resin enters. This is probably because it is easy. In other words, the air can easily escape, and since the resin flows upward along the inner surface of the tip of the body without being pushed back by the newly flowing resin, there is no need to apply more injection pressure than necessary. Therefore, it is thought that it is possible to prevent the resin from flowing (extruding) into the minute gap between the inner surface of the body and the outer surface of the male mold.

(Example 2) The tube container IA shown in FIG. 3 was manufactured by another example of the method of the present invention, and was a male mold in which the bottom surface of the cutout portion 22 in FIG. 2 was formed to be a substantially horizontal surface. It was obtained using.

In this case, if the structure is 14, the flow of molten resin into the inner surface of the body can be further prevented. That is, by making the inner surface angle of the thick wall 1 ring 7 smaller than the shoulder inner surface angle of the truncated conical portion 25 at the joint portion, the molten resin flowing down is caused to rise along the inner surface side of the tip of the body. This is because the head forming material is prevented from flowing (extruding) into unnecessary portions, and the temperature of the molten resin necessary for strong welding is stably maintained.

(Effects of the invention) (1) By providing the annular cutout part 22 on the male mold, the injection space at the joint part 6 is enlarged, so that the tip of the molten resin can be directed at the joint part in the left and right circumferential directions and in the upward direction. It has a structure that is easy to rotate, does not impair the fluidity of the head molding material, and as a result, the resin temperature necessary for strong welding can be maintained, and the upper end of the body and the injection resin layer forming the head The adhesive strength of the weld line can be increased.

(2) Since it is not necessary to increase the resin temperature or injection pressure during injection more than necessary, there is no need to extend the cooling time, and high productivity can be maintained, and the appearance of sink marks can be prevented. is also good.

(3) By bending the upper end of the body, its inner surface and truncated circle X1
Since the injection space of the joint is formed by the cut out part of the mold, the flow of molten resin is not forced into the small gap between the inner surface of the body and the outer surface of the male mold, and a flow characteristic is achieved in which the molten resin can easily rise. This makes it possible to mold joints without any resin protruding from the inside of the body. Therefore, even if the body is transparent, there is no problem in appearance, and when mounting it on a mandrel for decoration such as printing or painting on the outside of the body in the next process, (1γ positioning is accurate) This has the effect of allowing accurate decoration to be applied to the outer surface of the tube body.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view of a container (principal part) manufactured according to an example of the present invention, and Fig. 2 is a structural diagram of a mold showing the manufacturing process.
(1)) shows the state in which the sleeve-like body is attached to the male mold, (1)) shows the mold clamped state in which the female mold is combined, and (c) shows the state in which the molding material for the back of the mold clamped head is injected and the female mold is removed after cooling. FIG. 3 is a sectional view showing a container (principal part) manufactured according to another example of the present invention.
FIG. 1 lΔ...Squeeze tube container, 2...Sleeve-shaped body, 3...Head+1<, 6...Joint part, 8...
- Trunk tip, 28... Trunk upper end 1.26...11
L-shaped, 25 truncated cone quasi-part, 15...female type, 27...male type truncated cone tap 25 has a parallel inner surface, 21...injection space, 22...circular resection Part 29... Upper end of the excised part.

Claims (1)

[Claims] (1) A male mold 26 having a truncated cone (25) at the top and a female mold (26) having an inner surface (27) substantially parallel to the cone;
15) a mounting step of opening the mold and attaching the sleeve-shaped body 2 to the male mold, a mold clamping step of forming an injection space (21) by the male and female molds, and filling the injection space with molten resin. A squeeze tube container (which includes an injection process for injecting the resin and a cooling process for cooling the molten resin, and simultaneously molding the container head (3) and the joint part (6) between the body and the head) In the molding/joining method of 1), a male mold having an annular cutout (22) with a depth equal to or greater than the thickness of the container body plate is used as the male mold at the lower peripheral edge of the frustoconical part, and in the mounting step, , the sleeve-like trunk tip (8) is positioned above the lower end of the truncated cone of the male mold, and in the mold clamping step, the upper end (28) of the trunk is placed on the inner surface of the female mold. The injection space is formed by bending the mold along the male mold so that it faces the cut-out part (22), and positioning the body tip (8) below the upper end (29) of the opposing cut-out part (22). A method for forming and joining the head of a squeeze tube container.