JP2956491B2 - Composite lid of metal and synthetic resin and its manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite cover made of metal and resin for mounting on a container filled with a drug solution for injection, an infusion solution, and the like, and an apparatus for manufacturing the same.

[0002]

2. Description of the Related Art In general, a lid of a container such as a bottle filled with a drug solution for injection or an infusion solution (hereinafter, simply referred to as a drug solution) hangs from a top wall having an opening formed in a central portion and the top wall. It is a composite lid composed of an inner lid of a metal shell formed of an aluminum plate or the like made of a skirt wall, and an outer lid made of a synthetic resin that covers the top wall of the inner lid and covers the opening. In use, the outer lid is peeled off to expose the upper surface of the rubber plug from the opening of the inner lid, so that the injection needle can be punctured. Therefore, the outer lid of the composite lid is sealed in the normal state without easily peeling off from the upper surface of the metallic inner lid to keep the opening of the rubber stopper clean and easily peelable when used. Requirements are met. In order to satisfy this requirement, the present applicant has formed an adhesive area comprising an endless narrow cohesive failure adhesive-containing paint layer area on the top wall surface of a metal inner lid, and formed the inner lid after forming the upper lid. By heating by high-frequency induction heating, the metal-synthetic resin composite lid is made to melt the cohesive-breaking adhesive-containing paint layer so that the inner lid and the outer lid are partially bonded on the top wall surface of the inner lid. Proposed earlier.

[0003] On the other hand, to peel off the outer lid of this composite lid at the time of use, a fingertip is hung from above or peeled off, or in the case of a small bottle for an injectable drug solution, the bottle body is grasped with one hand to hold both sides of the lid. This is done by sandwiching between the thumb and the forefinger and pushing up one end of the outer lid with the tip of the thumb. Therefore, as a method of facilitating the peeling, it is conceivable to adopt a skirt wall structure in which the outer peripheral surface of the outer lid and the fingertip of the thumb are good.
For this reason, conventionally, the end of the skirt wall is expanded outward to improve the hooking of the thumb, or the unevenness or rough surface such as a step is formed on the outer peripheral surface of the skirt wall so as to enhance the friction effect. What has been proposed.

On the other hand, as a device for manufacturing a composite lid of metal and plastic, an aluminum inner lid is supported on a lower die, a split horizontal die is closed, and molten resin extruded from an extruder is placed on the top surface of the inner lid. Receiving and closing the upper mold, as the lower mold rises, press molding the molten resin with the top surface of the inner lid directly as the mold surface, and directly mold and integrate the outer lid of synthetic resin on the top wall to produce The applicant of the present invention has previously proposed the above-mentioned method (JP-A-1-213167, JP-A-1-317747, and JP-A-6-72457). In this manufacturing apparatus, after the mold is removed, the upper mold is first raised and opened, then the lower mold is raised and the molded product is removed from the horizontal mold, and then the horizontal mold is opened and the cap is taken out. .

[0005]

As described above, the outer lid is endlessly and partially adhered to the surface of the top wall of the inner lid through the endless adhesive area to improve the sealing performance and open the lid. In this case, it is possible to improve the peelability of the outer lid at the time, but it is also possible to form the end of the skirt wall of the outer lid with a large diameter or to form an annular unevenness or a rough surface on the outer peripheral surface of the skirt wall, thereby opening the outer lid. At the time, the hook on the thumb is improved, and the peelability of the outer lid is improved. However, forming the end portion of the skirt wall so as to increase the diameter and expanding outward increases the use amount of the resin material and increases the manufacturing cost, and the skirt wall expands outside the outer diameter of the bottle. And the outer lid peripheral surfaces come into contact with each other in the state of being stored in the packaging box, and are rubbed during transportation to generate fine dust, or the outer lid is accidentally peeled off by applying an impact to the outer lid. There is a risk that the sealing property of the lid may be impaired, and the storage volume increases, and the packaging box must be enlarged accordingly, which also increases the packaging cost.

Further, if irregularities or rough surfaces such as steps are formed on the outer peripheral surface of the skirt wall, fine dirt and dust easily accumulate on the outer peripheral surface of the lid, and this type of cap is particularly required to avoid dirt and dust. It is inconvenient.

On the other hand, a conventional apparatus for manufacturing a composite lid of a metal and a synthetic resin uses a molded composite lid that is fitted on a lower die when the upper die is opened when the die is removed after the molding is completed.
Since the lower end of the skirt wall is simply in contact with the horizontal mold surface, if the resin is not separated from the upper mold, the composite lid rises with the upper mold while the composite lid is in close contact with the upper mold. When the production of the next composite lid is performed in this state, a trouble occurs, and there is a problem that the apparatus stops. In particular, this is a serious problem in a rotary molding device operated at high speed.

SUMMARY OF THE INVENTION The present invention is intended to solve the problems of the structure of the conventional composite cap made of metal and synthetic resin and the problems of the manufacturing apparatus at a time, and it is possible to secure sufficient sealing performance. During use, the top lid can be easily peeled off, there is little adhesion of dust and dirt to the outer periphery of the top lid skirt, and there is no danger that the outer lids will come into contact with each other during transportation. An object of the present invention is to provide a composite lid of metal and plastic which can be surely formed and can be reliably die-cut even at a high speed operation, and a manufacturing apparatus therefor.

[0009]

SUMMARY OF THE INVENTION The present invention provides a metal inner lid having a top wall having an opening formed in the center and a cylindrical wall hanging down from the periphery of the top wall. In a composite lid of metal and synthetic resin comprising a synthetic resin outer lid having a top wall covering the top wall upper surface and a short skirt wall located on the upper outer periphery of the cylindrical wall, the outer peripheral surface of the skirt wall , At least a step surface in the thickness direction of the skirt wall
The above-mentioned configuration is characterized in that at least one step-shaped annular groove having a tapered surface inclined from the deepest portion toward the lower end of the outer peripheral surface of the skirt wall is formed. A composite lid could be obtained.

In the tapered surface of the annular groove, the difference between the diameter of the deepest part and the diameter of the lower end of the tapered surface is larger than the amount of resin shrinkage of the skirt wall portion on which the tapered surface is formed, and It should be within a range smaller than the elastic deformation limit of the wall portion. The annular groove preferably has a substantially horizontal stepped surface cut in the thickness direction from the outer peripheral surface of the skirt wall substantially parallel to the top wall.

The annular groove is not limited to one, but may be formed in two or more. Also, the top wall of the outer lid is peelably adhered to the top wall of the metal inner lid via an endless adhesive area,
The sealing property can be improved and the peeling property can be improved.

The apparatus for manufacturing a composite lid of the present invention for producing a composite lid of a metal and a synthetic resin is a composite lid of a metal and a synthetic resin by directly molding an outer lid made of a synthetic resin on an upper part of an inner lid made of a metal. And a lower mold for fitting and supporting the inner lid on the top surface, an upper mold for arranging the lower mold so as to be vertically movable in opposition to the lower mold, and a lower surface for the upper mold. A split type horizontal die having an upper die joining surface in close contact with the upper die and a lower skirt wall forming groove for forming a lower end portion of the skirt wall following the upper die. The forming groove is formed by providing a slight difference in diameter between the upper and lower portions and has a tapered surface. In addition, the terms indicating the directions such as “upper mold”, “lower mold” or up and down as described above,
For convenience, the expression is based on the case where the composite lid is manufactured with the top wall facing upward. When the composite lid is inverted by 90 degrees, the upper and lower sides are in the horizontal direction, and do not necessarily mean up and down.

[0013]

By forming an annular groove having a step surface formed substantially horizontally in the thickness direction on the skirt wall of the upper lid and a tapered surface inclined from the deepest portion toward the lower end of the outer peripheral surface, the outer lid can be removed at the time of peeling the outer lid. A fingertip hangs on the step surface, and the outer lid is easily peeled off. Therefore, since the lower end of the skirt wall does not need to be formed with a large diameter, material costs can be saved, and the ends of the skirt wall do not rub against each other in a boxed state.
There is no generation of plastic dust.

On the other hand, when the mold is removed after the molding of the composite lid, the tapered surface serves as a resistance to the horizontal die, thereby preventing the composite lid from coming into close contact with the upper die. And the taper surface, the diameter difference between the diameter of the deepest part and the lower end of the taper surface,
By forming the skirt wall portion on which the tapered surface is formed so as to be larger than the resin shrinkage amount after molding and smaller than the elastic deformation limit amount of the skirt wall portion, the resin is formed after molding. Even when contracted, the engagement with the horizontal mold can be maintained, and the engagement can be released within the elastically deformable range of the resin in that portion, the mold can be easily removed, and the skirt wall of the molded outer lid is formed. There is no inconvenience that may damage the device.

When the composite lid is mounted on a container, the tapered surface becomes a nearly vertical inclined surface and the cut surface becomes a ceiling surface. Dust is hard to collect particularly, and the outer peripheral surface of the lid can be kept clean.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 show one embodiment of the composite lid of the present invention. The composite lid 1 of the present embodiment includes an inner lid 2 made of metal and an outer lid 10 made of synthetic resin. Inner lid 2
Is press-formed from a metal plate such as an aluminum thin plate, has a top wall 3 and a cylindrical wall 4 hanging down from the periphery thereof, and an opening 5 is formed in the center of the top wall 3. The outer lid 10 has a large-diameter ceiling wall 11 that covers the upper surface of the top wall 3 of the inner lid.
And a short skirt wall 12 located on the upper periphery of the cylindrical wall
And a fitting portion 13 fitted to the opening 5.

The skirt wall 12 of the outer lid is formed in a very slightly tapered shape on the entire outer peripheral surface thereof so that the upper die can easily be removed at the time of molding. Step-shaped annular groove 15 is formed. The annular groove serves to prevent the composite lid from coming into close contact with the upper mold and prevent the composite lid from rising when the mold is removed from the mold after the molding of the composite lid, and to improve the function of catching a finger on the outer lid when the outer lid is peeled off. In addition, it is configured so as to satisfy the condition that dust and dust are unlikely to adhere and stay.

As a shape that satisfies these conditions, the annular groove 15 of the present embodiment is enlarged as shown in FIG.
In order to provide a slight dimensional difference such that the diameter of the lower part of the annular groove is slightly larger than that of the upper part, a predetermined depth is cut from the outer peripheral surface 14 of the skirt wall substantially parallel to the top wall (that is, horizontally). It is formed of a cutting surface 16 and a tapered surface 17 extending from the deepest portion of the cutting surface to the lower edge 18 of the outer peripheral surface. The outer peripheral surface lower edge 18 is located on an extension of the outer peripheral surface of the skirt wall.

The step surface 16 may be formed deeper in order to improve finger engagement. However, when the step surface is formed deeper, the inclination angle of the tapered surface increases, and the resistance to the upper die increases. The resistance to the horizontal die when the lower die rises also increases, and the outer lid may be damaged due to the fact that the die cannot be released or the die is forcedly released. In order to solve the problem, the tapered surface can maintain the engagement with the horizontal die even if the resin contracts after molding, and the engagement is within a range in which the resin of the portion can be elastically deformed. The tilt angle was set so that it could be solved.

The shrinkage of the resin on the skirt wall after molding does not change the diameter of the cylindrical wall of the metal inner lid. Therefore, the thickness of the skirt wall is targeted, and the shrinkage rate after molding is multiplied by Since the difference between the diameter of the annular groove and the diameter of the lower end of the tapered surface is larger than the amount of shrinkage of the skirt wall portion on which the tapered surface is formed, What is necessary is just to be in the range smaller than the elastic deformation limit of a part. Assuming that a ratio b / a of a difference b between the radius b of the outer peripheral surface of the skirt wall and the radius b of the depth position of the deepest portion of the annular groove with respect to the height a on the outer circumference from the lower end position of the annular groove to the deepest portion is the step value. The step value varies depending on the size of the composite lid, the type of synthetic resin forming the outer lid, and the like, but it has been confirmed that a range of approximately 0.05 to 0.2 is an appropriate range satisfying the above conditions. Was.

The composite lid is provided on the top surface of the top wall 3 of the inner lid 2 as shown in FIG. 2A so that the inner lid and the outer lid can be easily sealed and easily peeled off. A narrow ring-shaped endless adhesive area 20 is formed around the opening 5 to adhere the inner lid and the outer lid, for example, between the skirt wall of the outer lid and the cylindrical wall of the inner lid during steam sterilization of the composite lid. Even if steam, water droplets, germs, and the like enter the inside, sealing is performed so as not to reach the opening.
The endless adhesive area is disclosed in Japanese Patent Laid-Open Publication No.
As described in JP-A-667761 and JP-A-6-72457, an adhesive paint excellent in adhesion to metal and corrosion resistance, or between an adhesive paint alone and a metal and a synthetic resin. If no releasable adhesion is obtained, the coating is formed by using a cohesive breaking adhesive described in the above publication in this coating.

The endless adhesive area is formed by applying an adhesive paint to the outer surface of a metal plate in advance and exposing only a portion corresponding to the endless adhesive area of the top wall when punching and forming the upper surface. The part is formed as a print pattern to be printed, according to the pattern by using a masking ink for adhesive force control by a normal printing method, for example, by offset printing or the like, by printing other than the endless adhesive area The portion is masked with a masking ink layer 21 to form the endless adhesive area. In this manner, forming the endless adhesive area by printing on the metal plate in advance is particularly more efficient than forming the endless adhesive area after molding, and since printing is used, the endless adhesive area has a complicated shape. Can be done accurately and easily.

The peelability of the outer lid can be controlled by the position, area and shape of the endless adhesive area. The peelability becomes worse as the endless adhesive area is located closer to the outer peripheral portion of the top wall and the area is larger. On the contrary, the sealing performance is improved. In consideration of these conditions, in the present embodiment, it is formed as shown in FIG. 2A, but as another pattern, for example, a narrow width formed around the opening as shown in FIG. Ring-shaped endless bonding area 2
2 and a combination of an endless adhesive area 23 formed in a narrow ring shape at an interval outside thereof, and FIG. 2 (c).
As shown in the figure, the outer endless adhesive area 24 is formed in a zigzag shape, and the ring-shaped endless adhesive area 2 formed around the opening is formed.
5 and the like can be arbitrarily formed as needed.

Next, the mold assembly of the lid manufacturing apparatus will be described. The manufacturing apparatus of the present embodiment for manufacturing the above-mentioned composite lid of metal and plastic is characterized by a mold assembly.
Since it is the same as the manufacturing apparatus described in -72457,
Only the characteristic configuration will be described.

The molding die assembly 30 of the present embodiment comprises an upper die 31
, A lower die 32 and a split horizontal die 33, the main parts of which are shown in FIG.

The upper die assembly is disclosed in Japanese Patent Application Laid-Open No. 6-72457.
It is almost the same as that shown in column [0024] of the publication and FIG. 8, in which the high-frequency induction heating coil directly constitutes a part of the upper die, so that high-frequency heating can be performed immediately after molding. A mold recess is formed below the high-frequency induction heating coil, and an upper mold 31 made of ceramic is fitted into the mold recess. The upper die 31 is adhered and held to the lower surfaces of the high-frequency induction heating coil and the ferrite by an adhesive and is integrated, and can sufficiently withstand the pressure during molding even when formed thin.

The lower mold 32 is composed of a core member on the top of which the above-mentioned metal inner lid is fitted, is formed of ceramics which is an electrically insulating material, and is internally heated and cooled so that heating and cooling can be performed. A mechanism is incorporated.

Similarly, the horizontal die 33 is formed of ceramics, and has a semicircular inner surface 34 in contact with the outer periphery of the cylindrical wall 4 of the composite lid, and an upper die bonding surface 35 in close contact with the lower surface of the upper die. And a skirt wall outer peripheral lower part which forms the skirt wall outer peripheral lower part having the fitting groove at the lower end part of the skirt wall 12 following the upper die at the corner inner peripheral edge where the semicircular inner peripheral surface and the upper mold joining surface are joined. A mold surface 36 is formed. The skirt wall lower forming groove 36 has a tapered surface 37 inclined to form a tapered surface from the deepest portion in the thickness direction of the outer lid skirt wall 12 toward the lower peripheral surface of the skirt wall, and And a horizontal mold surface 38 forming the lower end surface of the skirt wall having the width of the lower end surface.

The tapered surface 37 is formed to be inclined at an inclination angle that matches the step value of the outer lid. Therefore, when the upper die 31 is raised from the state shown in FIG. 3B, the tapered surface 37 is engaged with the outer peripheral portion of the lower end of the skirt wall, so that resistance can be given to the composite lid being raised.
Then, even if the resin shrinks after the molding, the engagement with the horizontal die can be maintained, and the engagement is set so as to be released within a range where the resin in the portion can be elastically deformed.

The composite lid manufacturing apparatus of this embodiment is configured as described above, and the composite lid is manufactured by the apparatus as follows.

The inner lid is stamped and formed by a press, and the upper lid is aligned and transported by a suitable transport device to the composite lid manufacturing apparatus, and supplied so as to fit the top of the lower die 32. As described above, the inner lid is already coated with an adhesive paint on the inner surface, the adhesive paint on only the endless adhesive area of the top wall is exposed on the outer surface, and the other portions are masked with a masking ink layer to be non-coated. It is a bonded or weakly bonded area. When the inner lid is supplied, the upper mold is in the raised position and is open, and the split horizontal mold is also separated from the lower mold and is open on both sides,
The metal inner lid 2 can be fitted to the top of the lower mold. The lower mold fitted with the inner lid is lowered to the lower position, and the split horizontal mold is closed. In this state, the mold assembly moves to the resin charging zone, where the molten resin extruded from the extruder is cut and dropped onto the inner lid 2. Thereafter, when the process moves to the molding zone, the upper mold assembly is lowered and the mold is clamped, and the outer lid 10 is formed by making the upper part of the inner lid 2 a part of the molding one side.
The outer lid 10 is integrally formed on the upper surface of the inner lid as shown in FIG.

Next, when the mold assembly reaches the high-frequency heating zone, the inner lid 2 is rapidly induction-heated, the adhesive paint layer is melted to exhibit adhesiveness, and the synthetic resin upper lid and the metal The inner lid is bonded through the endless bonding area 20. In this state, since the mold is still in the clamped state, a pressing force also acts on the bonding surface, and the synthetic resin upper lid and the metal inner lid are securely bonded. Next, forced cooling is performed in a pressurized state by the lower die assembly to which the refrigerant is supplied, and the molded resin is fixed. After being sufficiently fixed, as shown in FIG.
The upper die assembly 31 is raised. At this time, since the upper skirt wall forming surface is formed in a very slightly tapered shape, the upper die is easily pulled out, and the horizontal taper surface and the skirt wall taper surface engage to raise the skirt wall. The outer lid does not come into close contact with the upper mold and rises. Next, as the lower mold 32 rises, the composite lid fitted to the top thereof also rises. At this time, the horizontal tapered surface and the tapered surface of the skirt wall engage to provide resistance to the rise of the skirt wall, but since the engagement is within the range of elastic change of the resin, the tapered surface of the outer lid is The die can be easily removed without giving excessive stress.

From the state shown in FIG. 3D, the horizontal die is opened 33 and the composite lid is held by the holder for sucking and holding the outer peripheral portion of the skirt wall, and the lower die is lowered to take out the formed composite lid. Is transported to the next inspection step.

The skirt wall lower die groove 36 of Example horizontal 33, as shown in FIG. 3 (a), a width corresponding to the skirt wall lower end face of the upper die bonding surface 35 to a depth position of 1.0mm thick A horizontal mold surface 38 having 1.0 mm and a radius difference of about 0.1 mm from the end of the horizontal mold surface.
And a tapered surface 37 formed so that
The upper die has a skirt wall outer peripheral upper forming surface for forming a position above the step surface of the skirt wall, and a lower end radius of the upper die is approximately 0.1 mm larger than a radius of the split die upper die joining surface. 1
mm. According to the mold assembly as described above, in a composite lid having an outer lid having a skirt wall height of 4.0 mm as shown in FIG. Where the step value is about 0.1
Thus, the step surface 16 was formed horizontally, and a tapered surface was formed so as to reach the lower edge of the skirt wall from the bottom.

As a result, it was possible to satisfactorily remove the mold without any trouble in removing the mold at the time of molding, and to use the finger when using it, and to easily peel off the outer lid. In addition, the annular groove has a small step of only 0.1 mm and is formed at a lower portion of the skirt wall, so that it is almost inconspicuous. There is no danger of dust accumulation.

The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above embodiment, and various design changes can be made. For example, FIG. 4 shows another embodiment in which the shape of the annular groove of the outer lid of the composite lid of the present invention is changed, and shows a main part of the skirt wall in an enlarged manner. In FIG. 4A,
This embodiment shows an example in which the step surface 42 of the annular groove 41 of the skirt wall 40 is inclined downward from the horizontal plane. FIG. 4B shows an embodiment in which the annular groove 44 is formed apart from the lower end 45 of the skirt wall 43. FIG.
(C) shows an embodiment in which two annular grooves 47 and 48 satisfying the above conditions are formed in the skirt wall 46. In these drawings, the inner lid 2 and the outer lid 10 are indicated by using the same drawing symbols as in the above embodiment.

[0037]

The present invention has the following special effects. ADVANTAGE OF THE INVENTION According to the composite lid of this invention and its shaping | molding apparatus, sufficient sealing property can be ensured, the upper lid can be easily peeled off at the time of use, and there is little accumulation of dust and dirt on the outer periphery of the upper lid skirt, and transport There is no danger of the outer lids touching each other at the time, and the mold can be reliably removed during molding.
The die can be reliably removed even at high speed operation, and the problems of the structure of the conventional composite cap of metal and synthetic resin and the problems of the manufacturing apparatus can be solved at once.

In particular, according to the composite lid manufacturing apparatus of the present invention,
When removing the mold after molding the composite lid, the tapered surface becomes a resistance to the horizontal die, and the top surface of the molded outer lid is securely adhered to the upper die and reliably prevented from being lifted in an unstable state and causing trouble , And can be manufactured at a high speed operation, and the processing capacity can be improved.

In the tapered surface, the difference between the diameter of the deepest part and the lower end of the tapered surface is within a range that is larger than the amount of shrinkage of the skirt wall portion after molding and smaller than the elastic deformation limit of the portion. In this case, even if the resin shrinks after molding, the engagement with the horizontal mold can be maintained, and the mold can be easily removed from the mold, which causes damage to the skirt wall of the molded outer lid. Does not occur.

Since the inner surface of the top wall of the synthetic resin outer lid is adhered to the top wall surface of the metal inner lid through an endless adhesive area that can be peeled off, the outer lid has high sealing performance and can be easily formed. Can be peeled off.

[Brief description of the drawings]

FIG. 1A is a longitudinal sectional view of a composite lid of a metal and a synthetic resin according to an embodiment of the present invention, and FIG. 1B is a partially enlarged view thereof.

2 (a) to 2 (c) show examples of the shape of an endless adhesive area provided on the upper surface of the top wall of the inner lid, respectively.

3A and 3B show an embodiment of a molding die assembling apparatus of the composite lid manufacturing apparatus according to the present invention, wherein FIG. 3A is a cross-sectional view of a main part thereof, and FIG. 3B is a cross-sectional view of a main part in a state where molding of an outer lid is completed. (C) is a sectional view of an essential part in a state where the upper mold has risen from the state of (b), and (d) is a sectional view of the principal part in a state where the lower mold has risen from the state of (c).

4 (a) to 4 (c) are longitudinal sectional views of a skirt wall portion of the composite lid according to each embodiment in which the shape of the annular groove formed in the outer lid skirt wall of the composite lid of the present invention is different. .

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Composite lid 2 Inner lid 3 Top wall 4 Cylindrical wall 5 Opening 10 Outer lid 11 Top wall 12, 4
3, 46 Skirt wall 15, 40, 42, 45, 46 Annular groove 16, 41
Step surface 17 Taper surface 20, 22
２５25 Endless adhesive area 30 Mold assembly 31 Upper mold 32 Lower mold 33 Horizontal mold 36 Skirt wall lower molding surface 37 Tapered surface

Claims (6)

(57) [Claims] A metal inner lid having a top wall having an opening formed in a central portion and a cylindrical wall hanging down from the periphery of the top wall;
A metal-synthetic resin composite lid comprising a synthetic resin outer lid having a top wall covering the top wall upper surface and a short skirt wall located on the upper outer periphery of the cylindrical wall, which is provided on the inner lid in a detachable manner, On the outer peripheral surface of the skirt wall, at least one step-shaped annular groove having a tapered surface inclined at least from the deepest part of the step surface in the thickness direction of the skirt wall toward the lower end of the outer peripheral surface of the skirt wall is provided. A composite lid of a metal and a synthetic resin, which is formed. 2. The tapered surface of the annular groove has a difference in diameter between the deepest portion and the lower end of the tapered surface larger than the resin shrinkage of the skirt wall portion on which the tapered surface is formed, after molding. 2. The composite lid of claim 1, wherein said composite lid is within a range smaller than an elastic deformation limit of said skirt wall portion. 3. The composite lid of claim 1, wherein the annular groove has a substantially horizontal stepped surface cut in a thickness direction substantially parallel to the top wall from the outer peripheral surface of the skirt wall. 4. A composite lid of a metal and a synthetic resin according to claim 1, wherein said annular groove is formed in two rows. 5. The composite lid of a metal and a synthetic resin according to claim 1, wherein said top wall is detachably adhered to a top wall via an endless adhesive area. 6. A composite lid manufacturing apparatus for manufacturing a composite lid of metal and synthetic resin by directly molding an outer lid made of synthetic resin on an upper part of an inner lid made of metal, wherein the inner lid is fitted and supported on a top surface. A lower mold to be formed, an upper mold that is arranged to be movable vertically in opposition to the lower mold to form a cavity, and an upper mold joining surface that is in close contact with the lower surface of the upper mold, and that a skirt is formed following the upper mold. A split type horizontal die which opens to a horizontal plane having a skirt wall lower forming groove for forming the lower end of the wall, and the horizontal type skirt wall outer peripheral lower end forming surface has a slight difference in diameter between the upper part and the lower part. An apparatus for manufacturing a composite lid of a metal and a synthetic resin, characterized in that the apparatus has a tapered surface formed as described above.