JP6096151B2 - Insert molded product - Google Patents

Description

  The present invention relates to an insert molded product composed of an injection molded product having an inner layer and an outer layer different from each other, and more particularly, the primary injection molded product is inserted into a mold and then subjected to secondary injection molding. The present invention relates to an insert molded product in which an injection molded product and a secondary injection molded product are integrated by thermal fusion.

Conventionally, as an insert molded product, there is one in which an inner layer is formed by a primary injection molded product and an outer layer is formed by a secondary injection molded product.
In such an insert molded product, a pre-molded primary injection molded product is placed in a mold, and a molten resin for molding the secondary injection molded product is injected toward the outer surface of the primary injection molded product. The primary injection molded product and the secondary injection molded product are integrated with each other by heat fusion.

  In addition, a skin material having a resin layer on the surface is placed in the mold, and the mold cavity is filled with the molten resin of the core material, and the skin material and the core material are integrally molded by heat fusion. There is also a molded product by the method (for example, see Patent Document 1).

Japanese Patent No. 3690154

However, the conventional insert molded product in which the inner layer is a primary injection molded product and the outer layer is a secondary injection molded product has the following problems (1) to (3).
(1) At the time of injection molding of the secondary injection molded product, the inner surface of the primary injection molded product needs to be in close contact with the mold with almost no gap, and the inner surface of the primary injection molded product has a complicated shape, for example, the primary When there are protrusions such as threads on the inner surface of an injection molded product, it is difficult to eliminate the gap between the mold and if there is a gap, injection at the time of secondary injection molding in the gap The primary injection molded product may be deformed by the pressure.
(2) For example, when application to a container in which the lid and the container main body are assembled by screw fitting is necessary, when the alignment in the screw operation direction is required, the primary injection molded product is placed in the screw operation direction in the mold. It is necessary to arrange them without shifting, and it is necessary to take measures such as providing positioning means, resulting in complication of the mold structure and the like.
(3) Since an injection gate for injecting a molten resin for forming a secondary injection molded product is generally provided at or near the center of the top surface of the secondary injection molded product, the molten resin The product value is used in cases where the injection mark remains on the surface of the secondary injection molded product, that is, the conspicuous part of the outer surface of the insert molded product, so that the appearance is impaired and the appearance of the cosmetic product is emphasized. Cause a significant decrease in In addition, when an injection gate is provided in positions other than the center part of the top | upper surface of a secondary injection molded product, or its vicinity, a moldability will worsen and a molding yield will fall.

  Moreover, in the molded product by the lamination molding method, since the molten resin for molding the core material, which is a secondary injection molded product, is injected toward the skin material that is generally thinned, the skin material is There is a problem that it may be damaged by injection of molten resin.

  In view of the problems of the conventional insert molded product, the present invention can be easily molded even if the inner surface has a complicated shape, and does not require alignment with a mold during secondary molding. An object of the present invention is to provide an insert-molded product that can be prevented from being damaged by injection of a molten resin without impairing the appearance of the appearance.

In order to achieve the above object, an insert-molded product of the present invention comprises a primary injection-molded product that forms an outer layer and a secondary injection-molded product that forms an inner layer. Is placed in the mold such that its outer surface is in contact with the mold cavity surface, and a molten resin for molding the secondary injection molded product is injected toward a predetermined portion of the inner surface of the primary injection molded product. An insert molded product in which a primary injection molded product and a secondary injection molded product are integrated by thermal fusion so that the molten resin for the secondary injection molded product on the inner surface of the primary injection molded product collides with it. A thick part having a thickness greater than that of the peripheral part of the part is formed in the injected part.

  In this case, the mold cavity surface can be transferred to the outer surface of the primary injection molded product by the injection pressure of the molten resin received by the thick wall portion.

According to the insert molded product of the present invention, since the inner layer of the insert molded product is formed by the secondary injection molded product by performing the secondary injection molding, it can be easily molded even if the inner surface has a complicated shape. At the same time, alignment with the mold at the time of secondary molding becomes unnecessary.
In addition, since the molten resin for molding the secondary injection molded product is injected toward the inner surface of the primary injection molded product, the molten resin injection trace does not remain on the outer surface of the insert molded product, and the appearance There is no such thing as detracting from the appearance.
Further, the injected site as the primary injection molded product molten resin for the secondary injection molded product of the inner surface of the strikes, because thick-walled portion is thicker than the peripheral portion of the portion is formed By injecting the injected molten resin at the thick portion, it is possible to prevent the primary injection molded product from being damaged by the injection of the molten resin.

  Moreover, a decorative pattern can be easily formed on the outer surface of the primary injection molded product by transferring the mold cavity surface to the outer surface of the primary injection molded product by the injection pressure of the molten resin received by the thick wall portion. .

It is a figure which shows the container equipped with the lid | cover as an insert molded product which concerns on one Embodiment of this invention, (a) is a top view, (b) is a front view which fractures | ruptures and represents. It is a figure which shows the injection molded product which comprises the lid, (a) is a longitudinal cross-sectional view of the primary injection molded product which forms the outer layer of a lid, (b) is a longitudinal section of the secondary injection molded product which forms the inner layer of a lid FIG. It is a figure which shows insert molding of the same lid | cover, and is a state figure which has arrange | positioned so that a primary injection molded product may contact the cavity surface of a female type | mold in a mold open state. It is a figure which shows insert molding of the cover, and is a metal mold | die closed state figure. It is a figure which shows insert molding of the cover, and is a secondary injection molding implementation state figure.

Next, an embodiment of an insert molded product of the present invention will be described based on the drawings.
In addition, although embodiment described below is an example in which the insert molded product of this invention was applied to the lid | cover in the container for cosmetics, for example, it is not limited to this of course.

<Outline of container>
A container 1 shown in FIGS. 1A and 1B is configured by assembling a lid 3 on a container body 2 by screw fitting.
The container body 2 has a bottomed cylindrical shape, and a male screw 4 is formed on the upper outer peripheral surface thereof.
The lid 3 is integrally formed with an octagonal cylindrical portion 3a having an internal thread 5 that is threadedly engaged with the male screw 4 of the container body 2, and a dome-shaped portion 3b that covers the opening of the container body 2 through the step portion 3c. It is configured in a row.
A packing 6 that closes the opening of the container body 2 in close contact with the container body 2 is placed on the opening end of the container body 2. And the stepped portion 3c so as to be held on the open end of the container body 2 is held.

<Description of the detailed structure of the lid>
The lid 3 includes, for example, a primary injection molded article 11 made of a soft resin (including a blend of resins) such as an olefin thermoplastic elastomer or a styrene thermoplastic elastomer, and a secondary injection made of a hard resin such as polypropylene. The outer layer is formed of a relatively soft primary injection molded article 11 which is configured in combination with the molded article 12 and can obtain a soft touch and an anti-slip effect, and is relatively hard (rigid) secondary. The inner layer is formed by the injection molded product 12.

<Description of primary injection molded product>
As shown in FIG. 2 (a), the primary injection molded article 11 is formed in advance using a primary injection mold (not shown), and forms an outer layer of the cylindrical portion 3a of the lid 3. A dome-shaped outer layer wall 11b that forms an outer layer of the dome-shaped portion 3b of the lid 3 is integrally connected to a cylindrical-portion outer-layer wall 11a through a step portion 11c.
In the primary injection molded article 11, the thickness t is substantially uniform from the cylindrical portion outer layer wall 11a through the step portion 11c to the vicinity of the center portion of the dome shaped outer layer wall 11b.
Here, the wall thickness t can be set to an arbitrary value in accordance with the use of the insert molded product. However, when the wall thickness t exceeds 2 mm, the female mold 20b (cavity) at the time of insert molding described later is used. ), The transferability with respect to the shape of the mold surface is deteriorated. Therefore, when the purpose is transfer, it is preferably set to 2 mm or less.

<Description of thick part>
A thick portion 13 having a circular shape with a predetermined draft angle is formed at the central portion of the inner surface of the outer wall 11b of the dome-shaped portion and is thicker than the thickness t of the peripheral portion.
The thickness T of the thick portion 13 is set to about 1.5 mm to 2.5 mm, and is 1.2 t to 4.0 t, preferably 1.5 t to the thickness t of the peripheral portion. It is preferable to be in the range of 3.0 t.
That is, when the thickness T of the thick portion 13 is less than 1.5 mm, a part of the resin constituting the primary injection molded product 11 is melted by the injection of the molten resin when the secondary injection molded product 12 is molded. However, in order to avoid the primary injection molded article 11 from being damaged by the injection of the molten resin, the injection pressure must be lowered, which may lead to deterioration of moldability, If it exceeds 2.5 mm, molding failure occurs when the primary injection molded article 11 is molded. Specifically, an excessive bending stress acts on the boundary between the thick portion 13 and its peripheral portion, causing defects such as cracking and deformation. May occur.

<Description of secondary injection molded product>
As shown in FIG. 2B, the secondary injection molded product 12 forms the inner layer of the dome-shaped portion 3 b of the lid 3 on the cylindrical portion inner layer wall 12 a that forms the inner layer of the cylindrical portion 3 a of the lid 3. A dome-shaped inner layer wall 12b is integrally connected to each other via a step 12c.
The internal thread 5 in the cylindrical portion 3 a of the lid 3 is substantially engraved on the inner surface of the cylindrical portion inner layer wall 12 a in the secondary injection molded product 12.

  Next, insert molding of the lid 3 using the mold 20 for secondary injection molding will be described below mainly with reference to FIGS.

<Description of mold used for insert molding>
First, the structure of the mold 20 will be described.
As shown in FIG. 3, the mold 20 is configured by combining a male mold 20a and a female mold 20b that can move relative to the male mold 20a.
The female mold 20b has a mold cavity surface 21 that has been subjected to surface processing such as uneven processing for applying a decorative pattern or diamond cut surface processing.
A stepped portion 22 is formed in a portion corresponding to the stepped portion 3c of the lid 3 in the female mold 20b, in other words, a portion corresponding to the stepped portion 11c of the primary injection molded product 11.
As shown in FIG. 4, when the male mold 20a is closed with respect to the female mold 20b, the male mold 20a faces the thick portion 13 of the primary injection molded article 11 set in the female mold 20b. The molten resin for a secondary injection molded product extruded from a nozzle of an injection device (not shown) is injected from the injection gate 23 via the sprue 24.
In the state where the male mold 20a and the female mold 20b are closed, a space 25 having the same shape as the secondary injection molded article 12 is formed between the primary injection molded article 11 and the male mold 20a. Yes.

<Description of insert molding>
The insert molding of the lid 3 using the mold 20 described above is performed as follows.
First, as shown in FIG. 3, the primary injection-molded product 11 is formed so that the outer surface of the dome-shaped outer layer wall 11b of the preformed primary injection-molded product 11 is in contact with the mold cavity surface 21 of the female mold 20b. It arrange | positions in the female type | mold 20b.
Next, as shown in FIG. 4, the female mold 20b is closed with respect to the male mold 20a.
Next, as shown in FIGS. 4 to 5, the molten resin M for the secondary injection molded product extruded from the nozzle of the injection device (not shown) is caused to collide with the thick portion 13 through the sprue 24 and the injection gate 23. The molten resin M once injected by the thick wall portion 13 is poured into the space portion 25 so as to diffuse radially.
As a result, the primary injection molded product 11 and the secondary injection molded product 12 are integrated by thermal fusion, and the primary injection molded product 11 is affected by the injection pressure of the molten resin M received by the thick portion 13. The outer surface is pressed against the mold cavity surface 21, whereby the mold cavity surface 21 is transferred to the outer surface of the primary injection molded product 11, and a decorative pattern is formed on the outer surface of the primary injection molded product 11.
Then, after cooling and solidification, by performing a predetermined undercut process, the male mold 20a is released from the lid 3, and then the lid 3 is released from the female mold 20b, and the target insert molded product is obtained. Can be obtained.

<Description of effects>
According to the lid 3 that is the insert molded product of the present embodiment, the following effects (1) to (4) can be obtained.
(1) Since the inner layer of the lid 3 is formed by the secondary injection molded product 12 by performing the secondary injection molding, the inner surface can be easily molded even if it has a complicated shape having the internal thread 5. Positioning with respect to the mold (male mold 20a) at the time of secondary molding becomes unnecessary.
(2) Since the molten resin for molding the secondary injection molded product 12 is injected toward the inner surface of the dome-shaped outer layer wall 11b in the primary injection molded product 11, the molten resin injection trace is the outer surface of the lid 3. There is no such thing that remains in the appearance, and the appearance of the appearance is not impaired.
(3) In the central part of the inner surface of the dome-shaped outer layer wall 11b in the primary injection molded article 11, a thick part 13 thicker than the thickness t of the peripheral part of the central part is formed and injected. Since the molten resin is received by the thick wall portion 13, it is possible to prevent the primary injection molded product 11 from being damaged by the injection of the molten resin, thereby preventing the injection of the molten resin. Since the adverse effect on the primary injection-molded product 11 can be eliminated, the molding resin temperature, the injection speed, etc. can be set to be equivalent to that of normal injection molding.
(4) Since the injected molten resin is received by the thick portion 13, from the cylindrical portion outer layer wall 11a in the primary injection molded article 11 to the vicinity of the center portion of the dome-shaped portion outer layer wall 11b. The mold thickness t can be made substantially uniform, and the transfer of the mold cavity surface 21 to the outer surface of the primary injection molded article 11 using the injection pressure of the molten resin received by the thick portion 13 is smoother. The decorative pattern can be easily formed on the outer surface of the primary injection molded article 11.

  As mentioned above, although the insert molded product of the present invention has been described based on one embodiment, the present invention is not limited to the configuration described in the above embodiment, and the configuration is appropriately changed without departing from the gist thereof. Is something that can be done.

  The insert molded product of the present invention can be easily molded even if the inner surface has a complicated shape, and does not require alignment with the mold at the time of secondary molding, and without impairing the appearance. Since it has the property that it can be prevented from being damaged by injection of molten resin, the inner layer and the outer layer are composed of different injection-molded products, and one side is closed and the other side is opened, for example It has a deep shape such as a hemispherical shape or a bottomed cylindrical shape, and can be suitably applied to a container body or a lid.

1 container 2 container body 3 lid (insert molded product)
DESCRIPTION OF SYMBOLS 11 Primary injection molded product 12 Secondary injection molded product 13 Thick part 20 Mold 20a Male mold 20b Female mold 21 Mold cavity surface

Claims (2)

A primary injection-molded product that forms an outer layer and a secondary injection-molded product that forms an inner layer, and the pre-molded primary injection-molded product in the mold so that its outer surface is in contact with the mold cavity surface The primary injection molded product and the secondary injection molded product are thermally melted by injecting molten resin for molding the secondary injection molded product toward a predetermined portion of the inner surface of the primary injection molded product. a insert molded article obtained by integrating by wear, in the injected site as the primary injection molded product molten resin for the secondary injection molded product of the inner surface of the strikes, thicker than the peripheral portion of the site insert molding, characterized in that is formed by thick-walled portion is formed. The insert molded product according to claim 1, wherein the mold cavity surface is transferred to the outer surface of the primary injection molded product by the injection pressure of the molten resin received by the thick wall portion.

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