JP6870581B2 - Manufacturing method of injection compression molded products - Google Patents

Description

The present invention relates to a method for producing an injection compression molded product.

There is an injection compression molding method as one of the methods for producing a resin molded product by injecting molten resin into a mold. The injection compression molding method includes a mold opening step, an injection step, a compression step, and a cooling step. In the mold opening process, the molds are held at intervals slightly larger than the specified intervals. In the injection process, the molten resin is injected at intervals of the molds. In the compression step, the entire pressure is applied to the mold so that the distance between the molds is a specified interval. In the cooling step, the mold is cooled while the entire pressure is applied to the mold, and after the cooling is completed, the mold is opened and the injection compression molded product is taken out.

Hereinafter, an example of the solidification of the molten resin in the cooling step of the conventional injection compression molding method will be described with reference to the cross-sectional views of the molds 201 and 202 shown in the examples of FIGS. 11 to 16. FIG. 11 shows the entire cross section of the molds 201 and 202 in which the gap 203 is formed in the mold opening step. In the region A201, the gap D211 of the thin-walled region A211 is narrow (the resin plate thickness is thin). , An example is shown in which the interval D212 of the thick region A212 is wide (the resin plate thickness is thick). Then, the molten resin is injected at the interval 203 in the injection step, and the overall pressure P200 is applied to the molds 201 and 202 so that the interval D200 between the mold 201 and the mold 202 becomes a predetermined interval in the compression step. Then, the cooling step of gradually cooling the mold is started in a state where the total pressure P200 is applied. Note that FIGS. 12 to 16 show enlarged views of the region A201 in FIG.

The example of FIG. 12 shows the state at the start of the cooling process. The distance 203 between the mold 201 and the mold 202 is filled with molten resin, and at the start of the cooling step, this resin is only the flowing molten layer 211. At the start of the cooling step, both the resin in the thin-walled region A211 and the resin in the thick-walled region A212 are only the molten layer 211.

The example of FIG. 13 shows a state in which the cooling step has progressed from the state of FIG. 12, and the resin in contact with the molds 201 and 202 is cured to form a thin solidified layer 212. In the example of FIG. 13, the resin in the thin-walled region A211 and the resin in the thick-walled region A212 both face the surfaces of the solidified layer 212 and the mold 202 in which the molten layer 211 faces the surface of the mold 201. It is sandwiched between the solidified layers 212.

The example of FIG. 14 shows a state in which the cooling step is further advanced from the state of FIG. 13, and shows a state in which the solidified layer 212 grows in the plate thickness direction and becomes thicker. In the example shown in FIG. 14, the molten layer 211 disappears in the thin-walled region A211 and the molten layer 211 remains in the thick-walled region A212.

The example of FIG. 15 shows a state in which the cooling step is further advanced from the state of FIG. 14, and the melting layer 211 is eliminated from both the thin-walled region A211 and the thick-walled region A212, and only the solidified layer 212 is formed. Indicates the finished state. After that, the mold 201 and the mold 202 are opened, and the injection compression molded product containing only the solidified layer 212 is taken out.

As described above, in the cooling step, the molten layer 211 of the fluid is gradually thinned, and when the cooling step is completed, the molten layer 211 disappears and only the solidified layer 212 is left. If the plate thickness of the injection compression molded product is uniform, the molten layer 211 in any region of the injection compression molded product becomes thin at substantially the same timing and eventually disappears. However, when the difference in the plate thickness of the injection compression molded product is relatively large, the solidified layer 212 is filled in the thin region A211 where the plate thickness is thin and the molten layer 211 is filled in the middle of the cooling step, as shown in the example of FIG. However, in the thick region A212 with a thick plate thickness, there may be a period in which a relatively thick molten layer 211 sandwiched between the solidified layers 212 remains. At this time, in the thin-walled region A211 where the plate thickness is thin, the pressure is concentrated on the solidifying layer 212 filled at the intervals of the molds, the state where the mold surface and the solidifying layer are in contact with each other is maintained, and cooling proceeds. , The surface condition looks good along the surface of the mold. However, as shown in the example of FIG. 16, in the thick region A212 where the plate thickness is thick, the resin of the molten layer 211 which is a fluid moves to the periphery and the molten layer 211 becomes thin, or the resin shrinks due to cooling. As a result, the solidifying layer 212 may be separated from the surfaces of the molds 201 and 202, and cooling may proceed in a state where a space 213 is formed between the surface of the solidifying layer 212 and the surfaces of the molds 201 and 202. is there. In this case, since the surface of the solidifying layer 212 is separated from the surfaces of the molds 201 and 202, the surface of the solidifying layer 212 (that is, the surface of the injection compression molded product) may be in an unattractive surface state. is there. For example, in the case where the injection compression molded product is a transparent resin window, when the above-mentioned unsightly surface condition is obtained, the scenery is viewed from an oblique direction with respect to the resin window through the resin window. It may appear to undulate.

In order to avoid separation between the solidified layer and the mold in the cooling step described above, for example, Patent Document 1 discloses a method for producing the synthetic resin molded product shown in FIGS. 17 and 18. In this manufacturing method, first, the cavities 102 of the molds 111 and 112 are slightly expanded beyond the specified volume, the molten resin is injected into the cavities 102 from the gate 103, and the cavities 102 are provided with the specified volume as shown in FIG. A total pressure is applied to the mold 111 and the mold 112 so as to reduce the size of the resin to the entire cavity 102. After that, as shown in FIG. 18, the movable portion 104 is moved upward and pressure is applied to the resin in the cavity 102 to complete the molding. That is, by applying a pressure different from the overall pressure applied to the mold 111 and the mold 112 to the thick region by using the movable portion 104, the solidified layer of the resin and the mold are separated from each other in the thick region. Avoiding that.

Japanese Unexamined Patent Publication No. 61-116519

In the method for manufacturing a synthetic resin molded product described in Patent Document 1, as shown in FIG. 18, pressure is applied to the resin in the cavity 102 by using the movable portion 104, but the movable portion 104 and the mold 112 Steps and the like are likely to be formed on the surface of the synthetic resin molded product at the boundary portion, and the surface appearance of the synthetic resin molded product may not be good. For example, when the region where pressure is applied by the movable portion 104 is a transparent resin window, it is not preferable because the appearance is not good if a step or the like is formed. Further, it is not preferable that the structure of the mold becomes complicated.

The present invention has been devised in view of these points, and even if the injection compression molded product has a non-uniform plate thickness and a relatively large difference in plate thickness depending on the region, the injection compression molded product has a good appearance. It is an object of the present invention to provide a method for producing an injection compression molded product capable of obtaining the above.

In order to solve the above problems, the first invention of the present invention is a method for manufacturing an injection compression molded product, which comprises a mold opening step of holding a mold at an interval larger than a preset predetermined interval, and the above-mentioned. The injection step of injecting the molten resin at the intervals of the molds, the overall compression step of applying the overall pressure to the molds so that the intervals of the molds are the specified intervals, and the plate thickness of the injection compression molded product A partial pressure, which is a pressure different from the total pressure applied to the mold, is applied to a thick region, which is a region thicker than the surrounding plate thickness, and a part of the mold is applied in the direction of the distance between the molds. This is a method for producing an injection-compressed molded article, which comprises a partial pressure applying step of applying the part pressure without moving the mold, and a cooling step of cooling the mold in a state where the total pressure and the partial pressure are applied.

The second invention of the present invention is the method for manufacturing an injection compression molded article according to the first invention, wherein the partial pressure is applied to the gate at the injection port where the molten resin is injected in the injection step. This is a method for manufacturing an injection compression molded product, in which the molten resin is applied by a force of discharging the molten resin at a predetermined pressure at intervals of the mold from a gate arranged in a thick region.

A third invention of the present invention is a method for producing an injection compression molded product according to the first invention or the second invention, wherein the molten resin is a transparent method for producing an injection compression molded product. ..

A fourth invention of the present invention is a method for manufacturing an injection compression molded product according to any one of the first to third inventions, wherein the injection compression molded product includes a vehicle back window and a vehicle back window. The thick region, including at least a portion of the periphery of the back window, is a method of manufacturing an injection compression molded article, which is the transparent back window.

According to the first invention, in the cooling step, by applying a partial pressure different from the total pressure applied to the mold to the thick region, the solidified layer in the thick region is separated from the mold surface. Can be prevented. Therefore, even if the plate thickness is not uniform and the difference in plate thickness is relatively large depending on the region, it is possible to obtain an injection compression molded product having a good appearance. In addition, since partial pressure is applied without moving a part of the mold in the direction of the distance between the molds, it is possible to prevent the formation of steps or the like in the thick region, and the injection compression molded product has a good appearance. Can be obtained.

According to the second invention, a partial pressure is applied by a force for discharging a molten resin at a predetermined pressure at intervals between molds from a gate arranged in a thick region. As a result, pressure can be applied to the molten layer in the thick-walled region, so that it is possible to appropriately prevent the solidified layer in the thick-walled region from separating from the mold surface. In addition, since partial pressure is applied without moving a part of the mold in the direction of the distance between the molds, it is possible to prevent the formation of steps or the like in the thick region, and the injection compression molded product has a good appearance. Can be obtained.

According to the third invention, for example, even if the injection compression molded product is a transparent resin window, it is possible to obtain an injection compression molded product having a good appearance.

According to the fourth invention, even if the thick region is the back window (transparent) of the vehicle, it is possible to obtain an injection compression molded product having a good appearance.

It is a figure explaining the example of the injection compression molded article manufactured by the manufacturing method of the injection compression molded article of this invention. It is a flowchart explaining each process of the manufacturing method of the injection compression molded article of this invention. It is sectional drawing of the mold (central part) explaining the mold opening process. It is sectional drawing of the mold (central part) explaining an injection process. It is sectional drawing of the mold (central part) explaining the whole compression process. It is sectional drawing of the mold (central part) explaining the partial pressure application process. It is sectional drawing of the mold (central part) explaining a cooling process. It is sectional drawing explaining the state of resin at the start time of a cooling process. It is sectional drawing explaining the state of resin at the intermediate time point of a cooling process. It is sectional drawing explaining the state of a resin at the end time of a cooling process. It is sectional drawing of the mold (center part) explaining the manufacturing method of the conventional injection compression molded article. It is sectional drawing explaining the state of the resin at the start time of the cooling process of the conventional manufacturing method of an injection compression molded article. It is sectional drawing explaining the state of the resin in the state which the cooling process progresses from the state of FIG. It is sectional drawing explaining the state of the resin in the state which further advanced the cooling process from the state of FIG. It is sectional drawing explaining the state of the resin in the state which further advanced the cooling process from the state of FIG. FIG. 3 is a cross-sectional view illustrating a state in which the solidified layer in the thick region is separated from the mold surface in the state of the resin shown in FIG. It is a figure explaining the example of the manufacturing method of the conventional synthetic resin molded article. It is a figure explaining how the movable part of a mold is moved upward in a cooling process, and partial pressure is applied to resin by a movable part in the conventional manufacturing method of a synthetic resin molded article.

● [Appearance of injection compression molded product (Fig. 1)]
Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows an example of the appearance of the back door 40 of a vehicle manufactured by using the method for manufacturing an injection compression molded product. The back door 40 described in the present embodiment has a roof portion 41, a spoiler portion 42, a rear frame portion 43, a rear side portion 44, a back window 45, and the like, and is integrally molded with resin. It may have 45 and at least a part around the back window 45. The back window 45 is colorless and transparent, but the parts other than the back window 45 are colored parts that are opaque, for example, by painting.

When the back door 40 shown in the example of FIG. 1 is manufactured as an injection compression molded product integrally molded with resin, the thickness of the colorless and transparent back window 45 region is thicker than the thickness of the surrounding region. In the case of meat, in the conventional method for producing an injection compression molded product, as described above with reference to FIG. 16, the solidified layer of the back window 45 may be separated from the mold surface during the cooling step. When the solidified layer of the back window 45 is separated from the mold surface in the middle of the cooling process, the surface state of the back window 45 becomes unattractive. For example, when the surrounding scenery is viewed through the back window from an oblique direction with respect to the back window, the scenery may appear to be wavy. If the injection compression molded product is manufactured by the method for manufacturing the injection compression molded product described in the present embodiment, the above-mentioned unsightly state can be avoided and the injection compression molded product has a good-looking surface state. Goods can be obtained in a stable manner.

● [Each process in the manufacturing method of injection compression molded products (Figs. 2 to 7)]
The flowchart shown in FIG. 2 shows each step in the manufacturing method of the injection compression molded product of the present embodiment. The manufacturing process of the injection compression molded product includes a mold opening step S10, an injection step S20, a total compression step S30, a partial pressure applying step S40, and a cooling step S50. The details of each step will be described below.

[Mold opening step S10 (FIG. 3)]
In the mold opening step S10, as shown in FIG. 3, the intervals in the preset predetermined intervals (in this case, the total compression step shown in FIG. 5, the partial pressure applying step shown in FIG. 6, and the cooling step shown in FIG. 7). The first mold 11 and the second mold 12 are held at intervals D1 slightly larger than D2). The interval D1 is set as appropriate. Further, the passages G1 and G2 are formed in advance in the first mold 11 in order to inject the molten resin at the distance K between the first mold 11 and the second mold 12 in the injection step which is the next step. It is a passage that has been made. The gate G1A, which is an injection port to the interval K in the passage G1, and the gate G2A, which is an injection port to the interval K in the passage G2, are set at appropriate positions that do not affect the appearance of the injection compression molded product. In the description of the present embodiment, as shown in FIG. 8, the gate G1A is arranged in the thin-walled region A11, and the gate G2A is arranged in the thick-walled region A12.

[Injection step S20 (FIG. 4)]
In the injection step S20, as shown in FIG. 4, the distance K (cavity) between the first mold 11 and the second mold 12 is K (cavity) from the gate G1A via the passage G1 and from the gate G2A via the passage G2. ), The molten resin 20 is injected. The first mold 11 and the second mold 12 are held at a preset holding temperature. The temperature of the molten resin 20 to be injected is, for example, about 300 [° C.]. The material of the resin is, for example, polycarbonate.

[Overall compression step S30 (FIG. 5)]
In the overall compression step S30, as shown in FIG. 5, the first mold 11 and the second mold 12 have a predetermined distance D2 between the first mold 11 and the second mold 12. A total pressure P1 is applied to 12. The overall pressure P1 may be applied to both the first mold 11 and the second mold 12 as movable bodies, or the first mold 11 is fixed and the second mold 12 is a movable body. The second mold 12 may be fixed and the first mold 11 may be applied to the first mold 11 as a movable body. By setting the interval between the first mold 11 and the second mold 12 as the interval D2 (interval D2 <interval D1), the molten resin injected in the interval K is crushed and the molten resin is uniformly distributed within the interval K. At the same time, the molten resin is filled in the interval K. In the overall compression step, the resin within the interval K is only the molten layer 21 in the molten state, and does not have the cured solidified layer.

[Partial pressure application step S40 (FIG. 6)]
In the partial pressure applying step S40, as shown in FIG. 6, the first mold 11 and the first mold 11 and the thick region A12 (see FIG. 8), which is a region where the plate thickness of the injection compression molded product becomes thicker than the surrounding plate thickness, A partial pressure P2, which is a pressure different from the total pressure P1 applied to the second mold 12, is applied without moving a part of the first mold 11 or the second mold 12 in the direction of the interval K. In this case, as shown in FIG. 6, the molten resin 20 having a predetermined pressure (in this case, the partial pressure P2) is supplied to the passage G2. As a result, as shown in FIG. 8, a partial pressure P2 is applied to the molten resin in the interval K by the force of discharging the molten resin into the interval K from the gate G2A arranged in the thick region A12. .. In order to apply partial pressure with the molten resin discharged from the gate arranged in the thick area, the gate is placed at the place where the molten layer 21 (see FIGS. 8 and 9) remains until just before the end of the cooling step. It is preferable that they are arranged. The value of the partial pressure P2 is appropriately set.

[Cooling step S50 (FIG. 7)]
In the cooling step S50, as shown in FIG. 7, the temperatures of the first mold 11 and the second mold 12 gradually increase from the holding temperature while maintaining the state in which the total pressure P1 and the partial pressure P2 are applied. It is lowered and cooled. Then, after cooling is completed and all the molten resin filled in the interval K is solidified, the interval between the first mold 11 and the second mold 12 is opened, and the injection compression molded product is taken out.

● [Changes in the solidified state of the resin during the cooling process (FIGS. 8 to 10)]
Next, changes in the solidified state of the resin during the cooling step will be described with reference to FIGS. 8 to 10. FIG. 8 shows the state of the resin at the start of the cooling process, FIG. 9 shows the state of the resin at the intermediate time of the cooling process, and FIG. 10 shows the state of the resin at the end of the cooling process. Shown. In the partial pressure applying step before the cooling step is started, the resin filled in the interval K is the molten layer 21 which is a resin in a molten state.

[State of resin at the start of the cooling process (Fig. 8)]
As shown in FIG. 8, at the time when the cooling step is started (at the time of the initial cooling), the resin in the interval K is the molten layer 21 which is mostly the resin in the molten state, and the solidified layer which is the solidified resin. 22 is formed thinly so as to face (contact) the surfaces of the first mold 11 and the second mold 12. When the cooling process is started and the temperatures of the first mold 11 and the second mold 12 are gradually lowered, the resin in contact with the surfaces of the first mold 11 and the second mold 12 begins to solidify. , A solidified layer 22 which is a solidified resin is formed on the surfaces of the first mold 11 and the second mold 12. Then, as the temperatures of the first mold 11 and the second mold 12 decrease, the solidified layer 22 grows and becomes thicker in the plate thickness direction, and the molten layer 21 becomes thinner. At the start of the cooling process, both the thin-walled region A11 in which the plate thickness D11 is thinner than the surrounding plate thickness and the thick-walled region A12 in which the plate thickness D12 is thicker than the surrounding plate thickness are the first mold 11 and A thin solidified layer 22 is formed at a position in contact with the surface of the second mold 12, and the molten layer 21 is sandwiched between the solidified layers 22.

A heater 15 is provided in the vicinity of the gate G2A so that the gate G2A is not blocked by the solidifying layer 22, and the temperature around the gate G2A is maintained at an appropriate temperature by the heater 15. .. Therefore, the molten resin pushed from the passage G2 at the partial pressure P2 melts the solidified layer 22 around the gate G2A to reach the molten layer 21, and uniformly applies the partial pressure P2 into the molten layer 21. As a result, the partial pressure P2 acts so as to press the solidified layer 22 from the inside of the molten layer 21 against the surfaces of the first mold 11 and the second mold 12. Therefore, in the thin-walled region A11 and the thick-walled region A12, it is possible to prevent the solidified layer 22 from being separated from the surfaces of the first mold 11 and the second mold 12.

[State of resin at the intermediate point of the cooling process (Fig. 9)]
FIG. 9 shows a state in which the temperatures of the first mold 11 and the second mold 12 are further lowered from the state of FIG. 8 to reach an intermediate time point of the cooling step. The state shown in FIG. 9 shows a state in which the molten layer 21 disappears and only the solidified layer 22 disappears in the thin-walled region A11, and the molten layer 21 and the solidified layer 22 coexist in the thick-walled region A12.

Since the thin-walled region A11 is filled with the solidifying layer 22, cooling proceeds in a state where the surface of the solidifying layer 22 is pressed against the surfaces of the first mold 11 and the second mold 12 by the total pressure P1. To go. Therefore, in the thin-walled region A11, the solidified layer 22 does not separate from the surfaces of the first mold 11 and the second mold 12, so that a good-looking surface is formed.

In the thick region A12, the solidified layers 22 facing (contacting) the surfaces of the first mold 11 and the second mold 12 and the molten layer 21 sandwiched between the solidified layers 22 are mixed. ing. If a part of the molten layer 21 which is a fluid moves to the surroundings or the resin shrinks in the plate thickness direction and the molten layer 21 becomes thin, the solidified layer 22 becomes the first mold 11 and the second mold. It may be separated from the surface of the mold 12. In order to avoid this, the partial pressure P2 due to the molten resin from the gate G2A is applied to the molten layer 21 in the thick region A12 (even if the molten layer 21 becomes thin, the partial pressure P2 from the gate G2A is applied. Since the molten layer 21 is replenished by the molten resin), the internal pressure of the molten layer 21 presses the solidified layer 22 against the surfaces of the first mold 11 and the second mold 12. Therefore, in the thick region A12, the solidified layer 22 does not separate from the surfaces of the first mold 11 and the second mold 12, so that a good-looking surface is formed.

[State of resin at the end of the cooling process (Fig. 10)]
FIG. 10 shows a state in which the temperatures of the first mold 11 and the second mold 12 are further lowered from the state of FIG. 9 to reach the end point of the cooling step. The state shown in FIG. 10 shows a state in which the molten layer 21 has disappeared and only the solidified layer 22 has disappeared in both the thin-walled region A11 and the thick-walled region A12. The temperature of the heater 15 is adjusted to an appropriate temperature according to the decrease in the temperature of the first mold 11 and the second mold 12 and the thickness of the molten layer 21 in the thick region A12.

As described above, the partial pressure P2 from the gate G2A cools both the thin-walled region A11 and the thick-walled region A12 without separating the solidifying layer 22 from the surfaces of the first mold 11 and the second mold 12. Can be advanced, resulting in a nice looking surface. Further, since the structure is not such that a part of the mold is a movable body and the movable body is moved in the direction of the interval K to apply partial pressure by the movable body, a step or the like may occur due to the boundary between the movable body and the mold. There is no mold, and the mold is not complicated.

The method for producing an injection compression molded product of the present invention is not limited to the steps described in the present embodiment, and various changes, additions, and deletions can be made without changing the gist of the present invention.

Further, the shape of the mold, the position of the gate, and the like are not limited to those described in the present embodiment, and the injection compression molded product to be manufactured is not limited to the back door of the vehicle. Further, the material and temperature of the resin are not limited to the material and temperature described in the present embodiment.

11 1st mold 12 2nd mold 15 Heater 20 Molten resin 21 Melted layer 22 Solidified layer 40 Backdoor (injection compression molded product)
41 Roof part 42 Spoiler part 43 Rear frame part 44 Rear side part 45 Back window A11 Thin wall area A12 Thick area D1, D2 Interval D11, D12 Plate thickness G1, G2 Passage G1A, G2A Gate K Interval P1 Overall pressure P2 Partial pressure S10 Mold opening process S20 Injection process S30 Overall compression process S40 Partial pressure application process S50 Cooling process

Claims (3)

It is a manufacturing method of injection compression molded products.
A mold opening process that holds the mold at intervals larger than the preset specified interval,
An injection process in which molten resin is injected at intervals of the mold, and
A total compression step of applying total pressure to the mold so that the distance between the molds is the specified interval, and
A partial pressure, which is a pressure different from the total pressure applied to the mold, is applied to a thick region, which is a region where the plate thickness of the injection compression molded product is thicker than the surrounding plate thickness, in one of the molds. A partial pressure applying step of applying the portion without moving the portion in the direction of the distance between the molds, and
A cooling step of cooling the mold with the total pressure and the partial pressure applied, and
Have,
The gate, which is the injection port from which the molten resin is injected in the injection step, includes a gate arranged in the thick-walled region and a region thinner than the plate thickness of the thick-walled region, which is the injection compression molded product. There is a gate that is arranged in a thin-walled area, which is an area where the plate thickness of is thinner than the surrounding plate thickness.
The partial pressure applied in the partial pressure applying step is
By not discharging the molten resin from the gate arranged in the thin-walled region, the molten resin is not applied.
A part of the mold is moved in the direction of the distance between the molds by applying the molten resin from a gate arranged in the thick region by a force of discharging the molten resin at a predetermined pressure at the distance between the molds. Grant without
Manufacturing method for injection compression molded products. The method for manufacturing an injection compression molded product according to claim 1.
The molten resin is transparent.
Manufacturing method for injection compression molded products. The method for producing an injection compression molded product according to claim 1 or 2.
The injection compression molded article includes a vehicle back window and at least a portion around the back window.
The thick area is the transparent back window.
Manufacturing method for injection compression molded products.

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