JPH1128748A - Molding method and molding apparatus for plastic molded products - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly accurate transfer surface and to reduce strain and deformation to achieve cost reduction by making the temp. of at least one place of the surface to be transferred of a molten resin lower than the temp. of a transfer surface during a period from a point of time starting the injection filling of a cavity with the molten resin to a point of time of the completion of the filling with the molten resin. SOLUTION: A mold is heated to be held to temp. below the softening temp. of a resin and a cavity 10 is filled with the molten resin heated to its softening temp. or higher by injection and resin pressure is generated on the transfer surfaces of mirror surface cores 6, 7. At the same time, the cooling air adjusted in its temp. by a temp. control apparatus 13 under predetermined pressure is supplied to a sink generating surface from an air passing hole 11 until the injection filling of the cavity 10 with the molten resin is completed. After the injection filling work of the molten resin is completed and the supply of cooling air is stopped, the interior of the cavity 10 is held to constant pressure to be cooled and pressure becomes almost zero to open the mold to take out the molded product. The generation of a sink on the transfer surface and the lowering of accuracy are prevented and transfer is faithfully performed by a short molding cycle to prevent the internal strain or deformation of the molded product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for molding a plastic molded article applied to an optical scanning system such as a laser beam printer, a facsimile, an optical device of a video camera, an optical disk, etc. The present invention relates to a method and apparatus for molding a plastic molded product capable of transferring a mirror surface or a pattern of fine irregularities onto a plastic molded product such as a prism with high accuracy.

[0002]

2. Description of the Related Art In general, an injection molding method involves injection-filling a molten resin into a cavity having a fixed volume in which a mold temperature is around a thermal deformation temperature of a molding resin, and gradually cooling while controlling a holding pressure. They open molds and take out molded products.
However, in this method, the temperature distribution during cooling of the resin becomes the pressure distribution as it is, so when molding thick or uneven molded products, the molding cycle can be shortened, but the residual pressure is applied to the uneven thickness portion. In addition, there is a disadvantage that high-precision molded products cannot be obtained due to the occurrence of sink marks in the thick portions.

As an injection molding method which does not cause such a problem, there is, for example, a method described in Japanese Patent Application Laid-Open No. 3-128218 (hereinafter referred to as a first conventional example). This can be done by forming a rough surface on the non-transfer surface opposite to the transfer surface on which the mirror surface, etc. are formed, by performing a surface treatment to reduce wettability, or by using a porous material to melt into the cavity. Immediately before the filling of the resin is completed, the injection is stopped and solidified by cooling without applying a holding pressure, thereby causing sink marks on the non-transfer surface due to the difference in adhesion between the molten resin and the transfer surface and the non-transfer surface, The occurrence of sink marks on the transfer surface is prevented.

[0004] Another molding method is disclosed in Japanese Unexamined Patent Publication No.
175115 (hereinafter referred to as a second conventional example). According to this method, molten resin is injected and filled into a cavity in which a porous member communicating with a compressed gas is disposed on a mold surface in contact with a non-transfer surface of a molded product, and the molten resin is filled after completion of filling into the cavity. During the cooling step from the pressure, the compressed gas is supplied to the non-transfer surface of the molded article through the porous member. In this case, the side surface of the cylindrical lens having a small lens thickness can be recessed.

As another molding method, there is a method described in JP-A-6-304973 (hereinafter referred to as a third conventional example). In this method, the non-transfer surface is communicated with the outside air through a vent hole, and the resin transfer surface and the non-transfer surface are formed between the start of injection filling of the molten resin into the cavity and the end of cooling of the resin. By generating a pressure difference between them, sink is induced on the non-transfer surface of the resin.

Another molding method is disclosed in Japanese Unexamined Patent Publication No.
Japanese Patent No. 315961 (hereinafter referred to as a fourth conventional example). By heating and maintaining the temperature of the transfer surface of the mold at a high temperature and heating the transfer surface of the resin to a high temperature from the start of injection filling of the molten resin into the cavity until the cooling of the resin is completed, A sink is induced on the non-transfer surface of the resin.

[0007]

However, in the molding method of the first conventional example, a rough surface is formed on a non-transfer surface facing a transfer surface, a surface treatment for reducing wettability is performed, Alternatively, since a porous material is used, there has been a problem that the processing cost of the mold is increased.

Further, since the injection is stopped immediately before the filling of the molten resin into the cavity so as not to apply the holding pressure, it is not possible to guide the sink direction and it is difficult to set the molding conditions. Therefore, there is a problem that the limitation on the shape of the molded product is increased. Furthermore, since the direction in which sink marks occur is the surface facing the molding surface, it can be applied only to mirrors, and is not suitable for molding lenses and the like.

In the molding method of the second conventional example,
Since the porous member that communicates with the compressed gas is provided on the mold surface that is in contact with the non-transfer surface of the molded product, the processing cost of the mold increases, and the management of the shape of the porous member is troublesome. It has become. In other words, when the effect of the porous member is large, the molten resin enters the holes and sinks, as well as hinders the release of the molded product. Also,
If the shape of the hole is wider than the wall surface of the mold, the resin enters and the molded product cannot be released.

Furthermore, since the compressed gas is supplied to the non-transfer surface of the molded product through the porous member during the cooling step from the holding pressure after the completion of filling the molten resin into the cavity, the cooling step is performed during the cooling step. Since the pressure difference is maintained between the non-transfer surface and the transfer surface of the resin, the internal distortion remains in the molded product after the mold is opened. In addition to a decrease in surface accuracy, there has been a problem that the entire molded product is deformed.

[0011] In the molding method of the third conventional example,
Since a pressure difference was generated between the transfer surface and the non-transfer surface of the resin between the start of injection filling of the molten resin into the cavity and the end of cooling of the resin, the same as in the second conventional example. During the cooling process, a pressure difference is maintained between the non-transfer surface and the transfer surface of the resin, so that after the mold is opened, internal distortion remains in the molded product. The transfer surface accuracy is reduced by the pressure, and the entire molded product is deformed.

Further, in the molding method of the fourth conventional example, the temperature of the transfer surface of the mold is maintained at a high temperature, and after the injection and filling of the molten resin into the cavity is started, the cooling of the resin is completed. The transfer surface side of the resin was heated to a high temperature until the temperature difference between the non-transfer surface and the transfer surface of the resin was maintained during the cooling process. The internal distortion remains in the molded product, and the residual pressure causes the transfer surface accuracy to deteriorate, and also causes the problem that the entire molded product is deformed.

Accordingly, the present invention provides a method for molding an inexpensive plastic molded article which can reliably induce sink marks on a non-transferred surface, obtains a highly accurate transfer surface, and has low distortion and little deformation. It is intended to provide a molding device.

[0014]

According to the first aspect of the present invention,
In order to solve the above problems, at least one or more non-transfer surfaces are formed on a surface other than the transfer surface while having at least one or more transfer surfaces, and at least one or more non-transfer surfaces are formed by the transfer surface and the non-transfer surface. Prepare a mold in which a cavity is defined, inject and fill a molten resin heated above the softening temperature into the cavity, and then generate resin pressure on the transfer surface to bring the resin into close contact with the transfer surface. After that, the resin is cooled to a softening temperature or lower, and then, in a molding method of a plastic molded article that is opened and taken out,
During the time from the start of the injection filling of the molten resin into the cavity to the completion of the filling of the molten resin, the temperature of at least one portion of the non-transfer surface of the molten resin is changed to the temperature of the resin on the transfer surface. It is characterized by being lower than that.

In this case, the non-transfer surface of the molten resin having a lower temperature than the transfer surface of the molten resin is solidified first and becomes high in viscosity. It is difficult to adhere to the transfer surface. Therefore, when the internal pressure of the non-transfer surface during the cooling step becomes substantially zero, the releasability is enhanced in preference to the non-transfer surface, and the sink is given priority over the surface in contact with other molds. Occur.

For this reason, it is possible to prevent the non-transfer surface from being preferentially shrunk to cause a sink on the transfer surface, and the desired transfer surface is faithfully transferred in a short molding cycle. In addition, since the temperature of the non-transfer surface of the molten resin is lower than the temperature of the resin of the transfer surface until the injection filling of the molten resin is completed and before the cooling process is started, the transfer surface and the non-transfer No surface temperature difference occurs, no internal distortion remains in the molded product after the mold is opened, it is possible to prevent the transfer surface accuracy from being reduced, and the entire molded product is deformed. Can be prevented.

According to a second aspect of the present invention, in order to solve the above-mentioned problems, at least one or more transfer surfaces are provided, and at least one or more non-transfer surfaces are formed on surfaces other than the transfer surfaces. A mold having at least one or more cavities defined by a surface and a non-transfer surface is prepared, a molten resin heated to a softening temperature or higher is injected and filled into the cavities, and then a resin pressure is applied to the transfer surface. After the resin is generated and brought into close contact with the transfer surface, the resin is cooled to a softening temperature or lower, and then the mold is opened and taken out. A gas layer is formed between at least one portion of the non-transfer surface of the molten resin and the mold during a period from the time when the filling is started to the time when the filling of the molten resin is completed. There.

In this case, a gas layer is formed between the non-transfer surface of the molten resin and the mold at the start of injection filling, so that the gas layer is brought into close contact with the non-transfer surface of the mold until the completion of injection filling of the molten resin. It becomes difficult. Also, when the injection filling is completed and the cooling is started, the formation of the gas layer is stopped, but at this time, the gas layer formed between the non-transfer surface of the resin and the mold is compressed by the internal pressure of the resin. Then, it is crushed and remains between the non-transfer surface of the resin and the mold. Then, as the internal pressure approaches zero, the residual gas expands, so that the non-transfer surface of the resin does not come into contact with the mold, and when the internal pressure becomes zero, the releasability increases with priority from the non-transfer surface. Sink occurs in preference to the surface in contact with other molds.

For this reason, the non-transfer surface is prevented from being preferentially shrunk to cause sink marks on the transfer surface, and the desired transfer surface is faithfully transferred in a short molding cycle. In addition, since the gas layer is formed between the non-transfer surface of the molten resin and the mold until the injection filling of the molten resin is completed and the process proceeds to the cooling process, the transfer surface and the non-transfer surface are formed during the cooling process. The pressure difference does not increase, the internal distortion does not remain in the molded product after the mold is opened, it is possible to prevent the transfer surface accuracy from being lowered, and the molded product is entirely deformed. Can be prevented.

According to a third aspect of the present invention, in order to solve the above problems, at least one or more transfer surfaces are provided, and at least one or more non-transfer surfaces are formed on surfaces other than the transfer surfaces. A mold having at least one or more cavities defined by a surface and a non-transfer surface is prepared, a molten resin heated to a softening temperature or higher is injected and filled into the cavities, and then a resin pressure is applied to the transfer surface. After the resin is generated and brought into close contact with the transfer surface, the resin is cooled to a softening temperature or lower, and then the mold is opened and taken out. Until the filling is completed, the temperature of the mold portion facing at least one or more of the non-transfer surfaces of the molten resin is set lower than the temperature of the mold portion facing the transfer surface. It is characterized by a door.

In this case, the non-transfer surface of the molten resin having a lower temperature than the transfer surface of the molten resin is first solidified to have a high viscosity. It is difficult to adhere to the transfer surface. Therefore, when the internal pressure of the non-transfer surface during the cooling step becomes substantially zero, the releasability is enhanced in preference to the non-transfer surface, and the sink is given priority over the surface in contact with other molds. Occur.

Therefore, the non-transfer surface is prevented from being preferentially shrunk to cause sink marks on the transfer surface, and the desired transfer surface is faithfully transferred in a short molding cycle. In addition, since the temperature of the non-transfer surface of the molten resin is lower than the temperature of the resin of the transfer surface until the injection filling of the molten resin is completed and before the cooling process is started, the transfer surface and the non-transfer No surface temperature difference occurs, no internal distortion remains in the molded product after the mold is opened, it is possible to prevent the transfer surface accuracy from being reduced, and the entire molded product is deformed. Can be prevented.

According to a fourth aspect of the present invention, in order to solve the above-mentioned problems, at least one or more transfer surfaces are provided, and at least one or more non-transfer surfaces are formed on surfaces other than the transfer surfaces. A mold having at least one or more cavities defined by a surface and a non-transfer surface is prepared, a molten resin heated to a softening temperature or higher is injected and filled into the cavities, and then a resin pressure is applied to the transfer surface. After the resin is generated and brought into close contact with the transfer surface, the resin is cooled to a softening temperature or lower, and then, in a method of molding a plastic molded product in which the mold is opened and taken out, at least the molten resin is contained in the cavity. From the time when the injection filling is started to the time when the filling of the molten resin is completed, the temperature of at least one of the non-transfer surfaces of the molten resin is set to the temperature of the resin on the transfer surface. A mold part facing at least one or more of the non-transfer surfaces of the molten resin, wherein a gas layer is formed between at least one of the non-transfer surfaces of the molten resin and the mold. Is combined with at least one of the methods of lowering the temperature of the mold portion facing the transfer surface.

In this case, the temperature of the non-transfer surface of the molten resin is made lower than the temperature of the resin of the transfer surface, a gas layer is formed between the non-transfer surface of the molten resin and the mold, the non-transfer surface of the molten resin. By combining at least one of the methods for lowering the temperature of the mold portion facing the transfer surface to the temperature of the mold portion facing the transfer surface, the non-transfer of the mold is completed until the injection filling of the molten resin is completed. It can be ensured that it does not adhere to the surface. As a result, when the internal pressure of the non-transfer surface during the cooling step becomes substantially zero, the releasability is enhanced in preference to the non-transfer surface and the sink is prioritized over the surface in contact with other molds. Can be generated reliably.

For this reason, the non-transfer surface is prevented from being preferentially shrunk to cause sink on the transfer surface, and the desired transfer surface is faithfully transferred in a short molding cycle. In addition, a gas layer is formed between the non-transfer surfaces of the molten resin until the injection filling of the molten resin is completed and before the cooling process is started, or the temperature of the non-transfer surface is lower than the temperature of the transfer surface. Therefore, it is possible to prevent the pressure difference and the temperature difference between the transfer surface and the non-transfer surface from increasing during the cooling step. For this reason, it is possible to prevent the internal distortion from remaining in the molded product after the mold is opened, to prevent the accuracy of the transfer surface from being lowered, and to deform the entire molded product. Can be prevented.

According to a fifth aspect of the present invention, in order to solve the above-mentioned problems, at least one or more transfer surfaces are provided, and at least one or more non-transfer surfaces are formed on surfaces other than the transfer surfaces. A mold having at least one or more cavities defined by a surface and a non-transfer surface is prepared, a molten resin heated to a softening temperature or higher is injected and filled into the cavities, and then a resin pressure is applied to the transfer surface. After the resin is generated and brought into close contact with the transfer surface, the resin is cooled to a softening temperature or lower, and then, in a method of molding a plastic molded product in which the mold is opened and taken out, at least the molten resin is contained in the cavity. From the time when the injection filling is started to the time when the filling of the molten resin is completed, the temperature of at least one of the non-transfer surfaces of the molten resin is set to the temperature of the resin on the transfer surface. A mold part facing at least one or more of the non-transfer surfaces of the molten resin, wherein a gas layer is formed between at least one of the non-transfer surfaces of the molten resin and the mold. At least one of a method of lowering the temperature of the mold portion facing the transfer surface and a method of pressing at least one of the non-transfer surfaces of the molten resin with a gas. It is characterized by being combined.

In this case, in addition to pressing at least one of the non-transferred surfaces of the molten resin with the gas after the injection filling of the molten resin into the cavity is started, in addition to the pressing of the non-transferred surface of the molten resin. The temperature is lower than the temperature of the resin on the transfer surface, a gas layer is formed between the non-transfer surface of the molten resin and the mold, and the temperature of the mold portion facing the non-transfer surface of the molten resin is the transfer surface. By combining one or more of the methods of lowering the temperature of the opposite mold portion, it is possible to ensure that the mold does not adhere to the non-transfer surface of the mold until the completion of the injection filling of the molten resin. As a result, when the internal pressure of the non-transfer surface during the cooling step becomes substantially zero, the releasability is enhanced in preference to the non-transfer surface and the sink is prioritized over the surface in contact with other molds. Can be generated reliably.

Therefore, it is possible to prevent the non-transfer surface from being preferentially shrunk to cause sink marks on the transfer surface, and the desired transfer surface is faithfully transferred in a short molding cycle. In addition, a gas layer is formed between the non-transfer surfaces of the molten resin until the injection filling of the molten resin is completed and before the cooling process is started, or the temperature of the non-transfer surface is lower than the temperature of the transfer surface. Therefore, it is possible to prevent the pressure difference and the temperature difference between the transfer surface and the non-transfer surface from increasing during the cooling step. For this reason, it is possible to prevent the internal distortion from remaining in the molded product after the mold is opened, to prevent the accuracy of the transfer surface from being lowered, and to deform the entire molded product. Can be prevented.

According to a sixth aspect of the present invention, there is provided a molding apparatus for molding a plastic molded product according to any one of the first, second, fourth and fifth aspects, wherein at least the mold is provided. It is characterized by having gas supply means for supplying gas adjusted to a predetermined pressure and temperature from one or more non-transfer surfaces to the non-transfer surface of the molten resin. In the present invention, when the temperature of the non-transfer surface of the molten resin is set lower than the temperature of the resin of the transfer surface, the gas at a low temperature and a predetermined pressure is melted from the gas supply means toward the non-transfer surface of the molten resin. By supplying the resin to the transfer surface, the temperature of the non-transfer surface can be made lower than the temperature of the transfer surface.

When a gas layer is formed between the non-transfer surface of the molten resin and the mold, a gas of a predetermined pressure is injected between the non-transfer surface of the molten resin and the mold from the gas supply means. You can do it. When the non-transfer surface of the molten resin is pressed by the gas, a high-pressure gas may be supplied from the gas supply means toward the non-transfer surface of the molten resin.

In this manner, the temperature of the non-transfer surface of the molten resin is reduced, the non-transfer surface is pressed, or a gas layer is formed between the non-transfer surface of the molten resin and the mold to reduce the cost. With this configuration, sink marks can be preferentially generated on the non-transfer surface. According to a seventh aspect of the present invention, in order to solve the above-mentioned problem, in the sixth aspect of the present invention, the gas supply means is formed in a mold portion having a non-transfer surface, and one end is opened in the cavity. It is characterized by having a vent and a supply device connected to the other end of the vent and supplying a gas adjusted to a predetermined pressure and temperature into the cavity through the vent.

In this case, the gas supply means can be constituted only by providing a ventilation hole in the mold and connecting a supply device to the ventilation hole, thereby preventing the structure of the mold from becoming complicated. . The invention according to claim 8 is a molding apparatus for molding the plastic molded product according to claim 3 in order to solve the above-mentioned problem, wherein at least one or more non-transfer surfaces of the mold have the mold. It is characterized in that cooling means for cooling the non-transfer surface is provided.

According to the present invention, the non-transfer surface of the mold is cooled by the cooling means, so that the non-transfer surface of the molten resin can be cooled. be able to.

[0034]

Embodiments of the present invention will be described below with reference to the drawings. First, FIGS. 1 to 3 are views showing a first embodiment of a molding method and a molding apparatus for a plastic molded product according to the present invention, and correspond to the invention described in any one of claims 1, 6 and 7.

First, the configuration will be described. FIG. 1 is a configuration diagram of a plastic molded product molded by the method for molding a plastic molded product of the present invention, and is directed to a lens as a molded product. The molded product formed in the present embodiment is not limited to a lens, but can be applied to an optical element such as a mirror and a prism. In FIG. 1, reference numeral 1 denotes a molded product, and mirror surfaces (transfer surfaces) 1a and 1b are formed on upper and lower surfaces of the molded product 1, and a reference surface (non-transfer surface) to be attached to another component is provided on one side surface. 1c is formed, and a sink generation surface (non-transfer surface) 1d on which the sink is to be generated is formed on the other side surface.

FIGS. 2 and 3 are structural views of a molding apparatus for molding the molded article 1 shown in FIG. In FIGS. 2 and 3, reference numeral 2 denotes a molding device, and a lower die 4 is attached to a mount 3 of the molding device 2. The lower die 4 is provided with an upper die 5 opposed thereto. The upper die 5 can be brought into contact with and separated from the lower die 4 by a mold clamping and opening device (not shown).

A plurality (four in this embodiment) of nests forming a cavity nest is interposed between the lower mold 4 and the upper mold 5. The cavity nests are provided opposite to each other, and mirror nests 6 and 7 having mirror surfaces 6a and 7a forming mirror surfaces 1a and 1b on the molded product, and provided with the nests 6 and 7 interposed therebetween. 1 includes a reference nest 8 and a sink nest 9 in which non-transfer surfaces 8a and 9a forming a reference surface 1c and a sink generation surface 1d are formed. A cavity 10 is defined by opposing surfaces of the nests 6 to 9. ing. The non-transfer surfaces 8a and 9a have minute irregularities.

FIG. 2 shows only half of the molding apparatus 2, and the other half is provided with a cavity insert having the same configuration as that described above. A sprue (not shown) is formed in the upper mold 5 and a sprue 6b communicating with the sprue is formed in the mirror insert 6 and the sprue (not shown) and the sprue 6b are shown in the cavity 10 through the sprue (not shown). No injection molding machine is used to inject molten resin.

The sink nest 9 is provided with a vent hole 11 having one end opening into the cavity 10 and the other end interposed in the lower mold 4 and the upper mold 5. Connected to the supply pipe 12. This supply pipe 12 is connected to a gas supply device 14 via a temperature control device 13, and is set to a predetermined pressure by the gas supply device 14 and is adjusted to a predetermined temperature by the temperature control device 13 (for example,
Air).

In this embodiment, the molten resin heated above the softening temperature is injected and filled into the cavity 10 while the mold is heated below the softening temperature of the resin. The temperature of the gas to be adjusted is about 3 ° C. lower than the temperatures of the mirror nests 6 and 7 and the reference nest 8.
The temperature is set to be low, and the sinking surface 1
A gas having a lower temperature than the mirror surfaces 1a and 1b and the reference surface 1c is supplied to d. The lower mold 4 and the upper mold 5 around the nests 6 to 9 are provided with a temperature adjusting mechanism such as a heater and an oil cooler.
Are heated and cooled, so that the nests 6 to 9 are heated and cooled.

In this embodiment, the temperature control device 13 and the gas supply device 14 constitute a supply device, and in addition to the temperature control device 13 and the gas supply device 14, the supply hole 11 constitutes a gas supply means. I have. Next, the operation will be described. In general injection molding, when molding a plastic optical element such as a lens, molding is performed under molding conditions for transferring the entire area (a condition in which the internal pressure is close to zero when the molded product is taken out). Since it is rapidly cooled from the time of entering the mold, a temperature distribution, a pressure distribution, a density distribution, and the like are generated, and the shape of the molded product is disturbed, and an internal distortion (deflection) occurs, which adversely affects the optical characteristics. .

On the other hand, by generating sink marks on a part of the molded product, transferability of the mold shape, internal distortion and deformation can be suppressed, but it is very difficult to identify the location of the sink marks. In the present embodiment, the point where the sink occurs can be specified. Hereinafter, a specific description will be given.

First, the mold is heated and held at a temperature lower than the softening temperature of the resin, the molten resin A heated to the softening temperature or higher is injected and filled into the cavity 10, and then the transfer surfaces 6a, 7a of the mirror inserts 6, 7 are filled. To generate resin pressure. At the same time as the injection and filling of the molten resin, a predetermined pressure is set from the gas supply device 14 and the temperature is adjusted by the temperature control device 13 and the cool air is supplied from the vent hole 11 to the sink generation surface 1d. Until the injection filling of the molten resin is completed.

At this time, since the sink generating surface 1d, which is lower in temperature than the mirror surfaces 1a and 1b, is solidified first and has a high viscosity, the non-transfer of the sink generating nest 9 is completed until the injection filling of the molten resin is completed. The sink generation surface 1d becomes difficult to adhere to the surface 9a. After the injection of the molten resin is completed and the supply of the cool air is stopped, the inside of the cavity 10 is kept at a constant pressure to cool the inside of the cavity 10. Next, when the pressure in the cavity 10 becomes substantially zero, the upper mold 5 is separated from the lower mold 4 and opened to take out the molded article 1 from the cavity 10.

At this time, the molded article 1 has a higher mold release property than the sink generation surface 1d and the sink occurs preferentially over the surface in contact with the other inserts 6 to 8, so that the mirror surfaces 1a and 1b are formed.
The sink is prevented from occurring, and the desired mirror surfaces 1a, 1
b can be faithfully transferred in a short molding cycle.
Further, the temperature of the sinking surface 1d of the molten resin is maintained at the mirror surface 1d before the injection and filling of the molten resin are completed and before the cooling process is started.
Since the temperature of the resin is lower than the temperatures of the resins a and 1b, the temperature difference between the mirror surfaces 1a and 1b and the sink surface 1d does not occur during the cooling process. Without remaining, the precision of the mirror surfaces 1a and 1b can be prevented from lowering, and the entire molded article 1 can be prevented from being deformed.

Further, a ventilation hole 11 is provided in the sink generation insert 9, and the temperature control device 13 and the gas supply device are provided in the ventilation hole 11.
Since the gas supply means can be configured only by connecting the 14, it is possible to prevent the structure of the mold from becoming complicated. 4 to 6 are views showing a second embodiment of a molding method and a molding apparatus for a plastic molded product according to the present invention,
It corresponds to the invention described in any one of claims 2, 6, and 7.
In this embodiment, since the shape of the molded product is the same as that of the first embodiment, FIG. 1 is referred to for the description of the molded product, and the same reference numerals are given to the same components as those of the first embodiment. The description is omitted.

4 and 5, a plurality of cavity nests (4 in this embodiment) are formed between the lower mold 4 and the upper mold 5.
Nests are interposed. The cavity nests are provided to face each other, and the mirror surfaces 1a, 1b
Mirror surface nesting 16, on which mirror surfaces 16a, 17a forming
And a non-transfer surface 18 provided between the nests 16 and 17 to form the reference surface 1c and the sink surface 1d on the molded product 1.
a and 19a are formed of a reference nest 18 and a shrinkage nest 19, and a cavity 20 is defined by opposing surfaces of the nests 16 to 19. The non-transfer surfaces 18a, 19
Small irregularities are formed on a.

A sprue (not shown) is formed in the upper die 5 and a sprue 16b communicating with the sprue is formed in the mirror insert 16 so that the cavity 20
Molten resin is injected and filled into the inside from an injection molding machine (not shown) through the sprue (not shown) and the sprue 16b. A ventilation hole 21 is formed in the sink generation nest 19, and the ventilation hole 21 has one end opening into the cavity 20 and the other end interposed between the lower mold 4 and the upper mold 5. Connected to tube 22.

The supply pipe 22 is connected to a gas supply device 23. The gas supply device 23 supplies a gas (for example, air) set at a predetermined pressure to the sink generation surface via the supply pipe 22 and the ventilation hole 21. Injection is made between 1d and the transfer surface 19a. In the present embodiment, the gas supply device 23 constitutes a supply device, and in addition to the gas supply device 23, the supply hole 21 and the supply pipe 22 constitute gas supply means.

Next, the operation will be described with reference to FIG. First, the mold is heated and held below the softening temperature of the resin, and the molten resin A heated above the softening temperature is injected and filled into the cavity 20, and then the resin pressure is applied to the transfer surfaces 16a and 17a of the mirror inserts 16 and 17. Generate. At the same time as the injection and filling of the molten resin, gas of a predetermined pressure is injected from the gas supply device 23 between the sink surface 1d and the transfer surface 19a. This injection operation is performed until the injection and filling of the molten resin into the cavity 20 is completed. Continue (see FIGS. 5A and 5B).

At this time, the non-transfer surface 19a and the sink generation surface 1d
Since the gas layer is formed during this time, the sink generation surface 1d is less likely to adhere to the non-transfer surface 19a until the injection filling of the molten resin is completed. When the injection of the molten resin is completed and the gas injection is stopped, the inside of the cavity 20 is kept at a constant pressure to cool the inside of the cavity 20. At this time, the gas layer formed between the resin sink generation surface 1d and the non-transfer surface 19a is compressed and crushed by the resin internal pressure, and remains between the resin sink generation surface 1d and the non-transfer surface 19a ( FIG. 5C).

The residual gas expands as the internal pressure approaches zero, so that the resin sink generation surface 1d does not contact the non-transfer surface 19a, and when the internal pressure becomes zero, priority is given to the non-transfer surface 19a. And the releasability is improved (FIG. 5D)
reference). Then, when the pressure in the cavity 20 becomes substantially zero, the upper die 5 is separated from the lower die 4 and opened to take out the molded product 1 from the cavity 20.

As a result, the sink surface 1d is preferentially sinked to prevent the mirror surfaces 1a and 1b from sinking, and the desired mirror surfaces 1a and 1b can be faithfully transferred in a short molding cycle. Further, the sinking surface 1 of the molten resin is maintained until the injection filling of the molten resin is completed and before the cooling process is started.
d Since a gas layer is formed between the non-transfer surfaces 19a, the pressure difference between the mirror surfaces 1a and 1b and the sink generation surface 1d does not increase during the cooling process, and the molded product 1 is formed after the mold is opened. Internal distortion does not remain, and it is possible to prevent the transfer accuracy of the mirror surfaces 1a and 1b from being lowered, and also to prevent the entire molded article 1 from being deformed.

The configuration of this embodiment can be achieved by the same configuration as that of the first embodiment. In this case, the gas supplied from the gas supply device 23 may be adjusted to the same temperature of the mold by the temperature adjustment device 13 of the first embodiment. In this case, as shown in FIG. 6, the mold is heated and held below the softening temperature of the resin, the molten resin heated above the softening temperature is injected and filled into the cavity 10, and then the mirror inserts 6, 7 A resin pressure is generated on the transfer surfaces 6a and 7a. In addition, gas supply device
A gas of a predetermined pressure is drawn from 23 and the generating surface 1d and the transfer surface 9a
And the injection operation is continued until the injection and filling of the molten resin into the cavity 10 is completed (FIGS. 6A and 6B).
reference).

At this time, the non-transfer surface 9a and the sink generation surface 1d
Since the gas layer is formed during this time, it is difficult for the sink surface 1d to be in close contact with the non-transfer surface 9a until the injection filling of the molten resin is completed. When the injection of the molten resin is completed and the injection of gas is stopped, the inside of the cavity 10 is maintained at a constant pressure to cool the inside of the cavity 10. At this time, the gas layer formed between the resin sink generation surface 1d and the non-transfer surface 9a is compressed and crushed by the resin internal pressure and remains between the resin sink generation surface 1d and the non-transfer surface 9a ( FIG. 6C).

Since the residual gas expands as the internal pressure approaches zero, the resin sink surface 1d does not come into contact with the non-transfer surface 9a. When the internal pressure becomes zero, the non-transfer surface 9a takes precedence. And the releasability is increased (FIG. 6D)
reference). Then, when the pressure in the cavity 10 becomes substantially zero, the upper mold 5 is separated from the lower mold 4 and opened to take out the molded article 1 from the cavity 10.

FIGS. 7 and 8 are views showing a third embodiment of the method and apparatus for molding a plastic molded article according to the present invention, and correspond to the third or eighth aspect of the present invention. In this embodiment, since the shape of the molded product is the same as that of the first embodiment, FIG. 1 is referred to for the description of the molded product, and the same reference numerals are given to the same components as those of the first embodiment. The description is omitted.

A plurality of (four in the present embodiment) nests forming a cavity nest are interposed between the lower mold 4 and the upper mold 5. The cavity nests are provided so as to face each other, and the mirror surfaces 26a and 26b forming the mirror surfaces 1a and 1b
mirror surface nests 26 and 27 in which a and 27a are formed, and this nest
26, 27 are provided, and are formed of a reference nest 28 and a shrinkage nest 29 having non-transfer surfaces 28a, 29a formed on the molded article 1 to form a reference surface 1c and a sinkage generation surface 1d. A cavity 30 is defined by the opposing surfaces 29. The non-transfer surfaces 28a and 29a have minute irregularities.

A sprue (not shown) is formed in the upper mold 5 and a sprue 26b communicating with the sprue is formed in the mirror insert 26 so that the cavity 30
The inside is filled with molten resin by injection molding from a not-shown injection molding machine via the not-shown sprue and sprue 26b. Further, a ventilation hole 31 is formed in the sink generation nest 29, and the ventilation hole 31 has an
The other end communicates with the outside air through a ventilation hole 33 and an exhaust pipe 35 formed in the lower mold 4 while communicating with the gas supply device 36 through a ventilation hole 32 and a supply pipe 34 formed in the bottom mold 4. I have.

The gas supply device 36 supplies a gas (for example, air) set at a predetermined pressure and adjusted to a predetermined temperature to the ventilation hole 31 through the supply pipe 34 and the ventilation hole 32. By exhausting air through the ventilation holes 33 and the exhaust pipe 35, the non-transfer surface 29 a of the sink nest 29 is cooled. In the present embodiment, the molten resin heated above the softening temperature is injected and filled into the cavity 30 while the mold is heated below the softening temperature of the resin. The gas temperature is about 3 ° C higher than the temperature of the mirror nests 26 and 27 and the reference nest 28
The temperature is set to be low and the sinking surface 29
To a is supplied a gas at a lower temperature than the mirror surfaces 26a, 27a and the non-transfer surface 28a.

In this embodiment, the gas supply device 36,
The supply pipe 34, the ventilation holes 31 to 33, and the exhaust pipe 35 constitute cooling means. Next, the operation will be described. First, before the injection filling of the molten resin is started, cold air set at a predetermined pressure from the gas supply device 36 and set at a predetermined temperature is supplied from the air holes 31 to the non-transfer surface 19 to supply the non-transfer surface. Cool 29a.

Next, the mold is heated and held at a temperature lower than the softening temperature of the resin, and the molten resin A heated to a temperature equal to or higher than the softening temperature is injected and filled into the cavity 30, and then the transfer surfaces 26a, 27a of the mirror inserts 26, 27 are filled. The operation of supplying the cold air is continued until the injection filling of the molten resin into the cavity 30 is completed. At this time, the sink generation surface 1d, which is lower in temperature than the mirror surfaces 1a and 1b, is solidified first and has a high viscosity, so that the non-transfer surface 29a of the sink generation insert 29 is completed before the injection filling of the molten resin is completed. The sink occurrence surface 1d is hard to adhere.

After the injection of the molten resin is completed and the supply of the cool air is stopped, the inside of the cavity 30 is cooled by keeping the inside of the cavity 30 at a constant pressure. Then the cavity
When the pressure in 30 becomes substantially zero, the upper die 5 is separated from the lower die 4 and opened to take out the molded product 1 from the cavity 10. As a result, the same effect as in the first embodiment can be obtained.

FIGS. 9 to 13 are views showing a fourth embodiment of a method and an apparatus for molding a plastic molded product according to the present invention, and correspond to the fifth or sixth aspect of the present invention. In this embodiment, since the shape of the molded product is the same as that of the first embodiment, FIG. 1 is referred to for the description of the molded product, and the same reference numerals are given to the same components as those of the first embodiment. The description is omitted.

A plurality of (four in the present embodiment) nests constituting a cavity nest are interposed between the lower mold 4 and the upper mold 5. The cavity nests are provided to face each other, and the mirror surfaces 41a and 1b are formed on the molded product.
a, 42a formed mirror surface nest 41, 42, and this nest
The molded product 1 is provided with a reference nest 43a and a shrinkage nest 44 on which a non-transfer surface 43a, 44a forming a reference surface 1c and a sink occurrence surface 1d is formed. A cavity 45 is defined by the facing surface 44. The non-transfer surfaces 44a and 45a have minute irregularities.

A sprue (not shown) is formed in the upper mold 5 and a sprue 41b communicating with the sprue is formed in the mirror insert 41, and a cavity 45 is formed.
Molten resin is injected and filled into the inside from a not-shown injection molding machine through the not-shown sprue and sprue 41b. Further, a ventilation hole 46 is formed in the sink generation insert 29, and the ventilation hole 46 has one end opening to the cavity 45 and the other end opening to the communication hole 47. The communication hole 47 is connected to a flow control device 50 through a ventilation hole 48 formed in the lower mold 4 and a supply pipe 49.
The flow controller 50 includes a pressure controller 51 and a temperature controller 52.
Is connected to the gas supply device 53 via the.

The gas supply device 53 constitutes a gas supply source, and the temperature adjustment device 52 adjusts the temperature of the gas supplied from the gas supply device 53. The pressure adjusting device 51 adjusts the pressure of the gas supplied from the gas supply device 53, and the flow adjustment device 50 adjusts the flow rate of the gas supplied from the gas supply device 53. I have.

The communication hole 47 communicates with an exhaust valve 56 via a ventilation hole 54 and an exhaust pipe 55 formed in the lower mold 4.
The gas supplied from the gas supply device 53 to the communication hole 47 is an exhaust valve.
When the valve 56 is opened, the gas is exhausted to the outside, and when the exhaust valve 56 is closed, the gas is supplied into the cavity 45. In the present embodiment, the flow control device 50, the pressure control device 51, the temperature control device 52, and the gas supply device 53 constitute a supply device, and in addition to this supply device, a vent 46, a communication hole 47, and a vent 48, 54, the supply pipe 49, the exhaust pipe 55 and the exhaust valve 56 constitute a gas supply means.

Next, the operation will be described with reference to FIGS. In the present embodiment, the temperature of the sinkage generating surface 1d of the molten resin is made lower than the temperature of the mirror surfaces 1a and 1b, and a gas layer is formed between the sinking surface 1d of the molten resin and the sinker nest 44. Any one or more methods of lowering the temperature of the sink generation insert 44 facing the sink generation surface 1d to the temperature of the mirror inserts 41 and 42,
The method is characterized by combining a method of pressing d with gas, and in this case, a description will be given of a combination of all methods.

First, the exhaust valve 56 is opened, and a slight amount of gas is supplied to the communication hole 47 by the flow rate adjusting device 50, so that the sink
44 is cooled (see FIG. 11A). At this time, if the flow rate of the gas is large, the cavity 45 passes from the communication hole 47 through the ventilation hole 46.
In order to prevent the gas from being supplied to the inside and to cool the mirror surface inserts 41, 42, etc., the flow rate is adjusted to such a degree that the gas is not supplied into the cavity 45.

At this time, the temperature may be adjusted by the temperature adjusting device 52 in order to cool the sink generating insert 44 effectively. Then, after heating and holding the mold below the softening temperature of the resin, before injecting and filling the molten resin heated above the softening temperature into the cavity 30, the flow rate and pressure of the gas by the flow rate adjusting device 50 and the pressure adjusting device 51. After the gas is supplied from the communication hole 47 into the cavity 45 through the ventilation hole 46, injection filling of the molten resin into the cavity 45 is started (see FIG. 11B).

At this time, the cooling effect of the resin can be enhanced by increasing the amount of gas supplied to the sink generating surface 1d, and the sink generating surface 1d can be pressed by increasing the gas pressure. With sinking surface 1d
An air layer can be formed between the sinker nest 44. Next, when the resin injection filling operation is completed (FIG. 12)
(See (a)), the exhaust valve 56 is closed, the pressure of the gas is adjusted by the pressure adjusting device 51 so as to obtain an appropriate gas pressure, and the inside of the cavity 45 is kept at a constant pressure to cool the inside of the cavity 45 ( (See FIGS. 12B and 12C).

Next, when the pressure in the cavity 45 becomes substantially zero, the upper mold 5 is separated from the lower mold 4 and opened to take out the molded product 1 from the cavity 45. As a result, the first
In addition to the same effects as those of the embodiment, since the sink generating surface 1d is always pressurized, the sink generating nest 44 moves away from the sink generating surface 1d.
d can be surely released, and the effect that the sink mark can be more reliably generated on the sink generation surface 1d can be obtained.

In this embodiment, the pressure adjusting device 51 and the like are provided.
As shown in FIG. 13, the flow rate adjusting device 50 may be connected to the factory air 57. In addition, in the embodiment, the sink generation surface 1d is always pressurized. However, without pressurization, at least from the time when the injection and filling of the molten resin into the cavity 45 is started until the filling of the molten resin is completed. Forming a gas layer between at least one or more of the non-transfer surfaces of the molten resin and the mold, wherein the temperature of at least one or more of the non-transfer surfaces of the molten resin is lower than the temperature of the resin on the transfer surface; Combining any one or more of the methods of forming the temperature of the mold portion facing at least one or more of the non-transfer surfaces of the molten resin to be lower than the temperature of the mold portion facing the transfer surface. You can just do it.

[0075]

According to the first aspect of the present invention, it is possible to preferentially sink the non-transfer surface of the molded article to prevent sink marks from occurring on the transfer surface, and to shorten the desired transfer surface to a short molding cycle. Can be faithfully transferred. In addition, since the temperature of the non-transfer surface of the molten resin is lower than the temperature of the resin of the transfer surface until the injection filling of the molten resin is completed and before the cooling process is started, the transfer surface and the non-transfer No surface temperature difference occurs, no internal distortion remains in the molded product after the mold is opened, it is possible to prevent the transfer surface accuracy from being reduced, and the entire molded product is deformed. Can be prevented.

According to the second aspect of the present invention, the non-transfer surface of the molded article can be preferentially shrunk to prevent the transfer surface from sinking, and the desired transfer surface can be faithfully formed in a short molding cycle. Can be transferred to In addition, since the gas layer is formed between the non-transfer surface of the molten resin and the mold until the injection filling of the molten resin is completed and the process proceeds to the cooling process, the transfer surface and the non-transfer surface are formed during the cooling process. The pressure difference does not increase, the internal distortion does not remain in the molded product after the mold is opened, it is possible to prevent the transfer surface accuracy from being lowered, and the molded product is entirely deformed. Can be prevented.

According to the third aspect of the present invention, the non-transfer surface of the molded article can be preferentially shrunk to prevent the transfer surface from sinking, and the desired transfer surface can be faithfully formed in a short molding cycle. Can be transferred to In addition, since the temperature of the non-transfer surface of the molten resin is lower than the temperature of the resin of the transfer surface until the injection filling of the molten resin is completed and before the cooling process is started, the transfer surface and the non-transfer No surface temperature difference occurs, no internal distortion remains in the molded product after the mold is opened, it is possible to prevent the transfer surface accuracy from being reduced, and the entire molded product is deformed. Can be prevented.

According to the fourth and fifth aspects of the present invention, it is possible to preferentially sink the non-transfer surface of the molded article to prevent sink marks from occurring on the transfer surface. Can be faithfully transferred. In addition, a gas layer is formed between the non-transfer surfaces of the molten resin until the injection filling of the molten resin is completed and before the cooling process is started, or the temperature of the non-transfer surface is lower than the temperature of the transfer surface. Therefore, it is possible to prevent the pressure difference and the temperature difference between the transfer surface and the non-transfer surface from increasing during the cooling step. For this reason, internal distortion can be prevented from remaining in the molded product after the mold is opened,
It is possible to prevent the accuracy of the transfer surface from being lowered and to prevent the entire molded product from being deformed.

According to the present invention, the temperature of the non-transfer surface of the molten resin is lowered, the non-transfer surface is pressed, or a gas layer is formed between the non-transfer surface of the molten resin and the mold. It is possible to preferentially generate sink marks on the non-transfer surface with an inexpensive configuration. According to the seventh aspect of the present invention, a gas supply means can be configured by merely providing a ventilation hole in the mold and connecting a supply device to the ventilation hole, thereby preventing the structure of the mold from becoming complicated. can do.

According to the present invention, the non-transfer surface of the mold can be cooled by the cooling means, so that the non-transfer surface of the molten resin can be cooled. Can be preferentially generated.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment of a method and an apparatus for molding a plastic molded article according to the present invention, wherein (a) is a perspective view of a molded article molded by the molding method,
(B) is a side view of the molded article showing the sink generation area,
FIG. 3C is a sectional view taken along the line AA in FIG.

FIG. 2 is a view showing a molding apparatus according to the first embodiment;
(A) is a cross-sectional view showing a half part of the entire configuration,
(B) is a perspective view of the cavity nest.

3A is a cross-sectional view in the X direction of FIG. 2B, and FIG. 3B is a cross-sectional view in the Y direction of FIG. 2B.

FIG. 4 is a view showing a second embodiment of a method and an apparatus for molding a plastic molded product according to the present invention, and is a cross-sectional view showing a half portion of the molding apparatus.

FIG. 5 is a diagram showing a procedure of a molding method according to a second embodiment.

FIG. 6 is a view showing another procedure of the molding method of the second embodiment.

FIG. 7 is a view showing a third embodiment of a method and an apparatus for molding a plastic molded product according to the present invention, and is a schematic top view of the molding apparatus.

FIG. 8 is a diagram showing a procedure of a molding method according to a third embodiment.

FIG. 9 is a view showing a fourth embodiment of a method and an apparatus for molding a plastic molded product according to the present invention, and is a schematic top view of the molding apparatus.

10A is a perspective view of a cavity nest according to a fourth embodiment, FIG. 10B is a cross-sectional view in the X direction of FIG. 10A, and FIG. 10C is a cross-sectional view in the Y direction of FIG. .

FIG. 11 is a diagram illustrating a procedure of a molding method according to a fourth embodiment.

FIG. 12 is a diagram illustrating a procedure of a molding method subsequent to FIG. 11 (b).

FIG. 13 is a schematic configuration diagram illustrating another aspect of the molding apparatus of the fourth embodiment.

[Description of Signs] 1 Molded product 2 Molding device 6, 7, 16, 17, 26, 27, 41, 42 Mirror surface insert (die) 6a, 7a, 16a, 17a, 26a, 27a, 41a, 42a
Mirror surface (transfer surface) 8, 18, 28, 43 Reference nest (die) 9, 19, 29, 44 sinker nest (die) 9a, 19a, 29a, 44a Non-transfer surface 11, 46, 48, 54 Pore (gas supply means) 13, 52 Temperature controller (supply device, gas supply means) 14, 53 Gas supply device (supply device, gas supply means) 21 Vent (gas supply means) 22, 49 Supply pipe (gas supply Means) 31-33 Vent hole (cooling means) 34 Supply pipe (cooling means) 35 Exhaust pipe (gas supplying means) 36 Gas supplying device (cooling means) 47 Communication hole (gas supplying means) 50 Flow rate adjusting device (supplying device, Gas supply means) 51 Pressure regulator (supply device, gas supply means) 55 Exhaust pipe (gas supply means) 56 Exhaust valve (gas supply means)

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kiyotaka Sawada 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd.

Claims (8)

[Claims] An image forming apparatus comprising: at least one transfer surface; at least one non-transfer surface formed on a surface other than the transfer surface; and at least one cavity formed by the transfer surface and the non-transfer surface. Prepare the formed mold, injection-filled molten resin heated above the softening temperature in the cavity, then, after applying a resin pressure on the transfer surface to bring the resin into close contact with the transfer surface, The resin is cooled to a softening temperature or lower, and then, in a method of molding a plastic molded product, the mold is opened and taken out, from the time when injection filling of the molten resin is started into the cavity until the filling of the molten resin is completed. Wherein the temperature of at least one portion of the non-transfer surface of the molten resin is set lower than the temperature of the resin on the transfer surface. And a non-transfer surface having at least one transfer surface and at least one non-transfer surface formed on a surface other than the transfer surface, wherein at least one cavity is defined by the transfer surface and the non-transfer surface. Prepare the formed mold, injection-filled molten resin heated above the softening temperature in the cavity, then, after applying a resin pressure on the transfer surface to bring the resin into close contact with the transfer surface, The resin is cooled to a softening temperature or lower, and then, in a method of molding a plastic molded product, the mold is opened and taken out, from the time when injection filling of the molten resin is started into the cavity until the filling of the molten resin is completed. Wherein a gas layer is formed between at least one of the non-transfer surfaces of the molten resin and the mold. And a non-transfer surface having at least one transfer surface and at least one non-transfer surface formed on a surface other than the transfer surface, wherein at least one cavity is defined by the transfer surface and the non-transfer surface. Prepare the formed mold, injection-filled molten resin heated above the softening temperature in the cavity, then, after applying a resin pressure on the transfer surface to bring the resin into close contact with the transfer surface, In the method of molding a plastic molded article, wherein the resin is cooled to a softening temperature or lower, and then the mold is opened and removed, the injection of the molten resin into the cavity is completed until the injection of the molten resin is completed. At least one of the transfer surfaces
A method of molding a plastic molded product, wherein a temperature of a mold portion facing at least a portion is lower than a temperature of a mold portion facing the transfer surface. 4. A printing apparatus having at least one transfer surface and at least one non-transfer surface formed on a surface other than the transfer surface, wherein at least one cavity is defined by the transfer surface and the non-transfer surface. Prepare the formed mold, injection-filled molten resin heated above the softening temperature in the cavity, then, after applying a resin pressure on the transfer surface to bring the resin into close contact with the transfer surface, In a method for molding a plastic molded article, in which the resin is cooled to a softening temperature or lower, and then the mold is opened and taken out, the filling of the molten resin is completed at least from the time when the injection filling of the molten resin is started in the cavity. By then,
A gas between at least one or more of the non-transfer surfaces of the molten resin and a mold, wherein the temperature of at least one or more of the non-transfer surfaces of the molten resin is lower than the temperature of the resin on the transfer surface; Any one of the methods of forming a layer, wherein a temperature of a mold portion facing at least one or more of the non-transfer surfaces of the molten resin is lower than a temperature of a mold portion facing the transfer surface. A method for molding a plastic molded article, comprising a combination of the above. 5. A printing apparatus having at least one transfer surface and at least one non-transfer surface formed on a surface other than the transfer surface, wherein at least one cavity is defined by the transfer surface and the non-transfer surface. Prepare the formed mold, injection-filled molten resin heated above the softening temperature in the cavity, then, after applying a resin pressure on the transfer surface to bring the resin into close contact with the transfer surface, In a method for molding a plastic molded article, in which the resin is cooled to a softening temperature or lower, and then the mold is opened and taken out, the filling of the molten resin is completed at least from the time when the injection filling of the molten resin is started in the cavity. By then,
A gas between at least one or more of the non-transfer surfaces of the molten resin and a mold, wherein the temperature of at least one or more of the non-transfer surfaces of the molten resin is lower than the temperature of the resin on the transfer surface; Any one of the methods of forming a layer, wherein a temperature of a mold portion facing at least one or more of the non-transfer surfaces of the molten resin is lower than a temperature of a mold portion facing the transfer surface. A method of molding a plastic molded product, comprising combining the above and a method of pressing at least one or more of the non-transfer surfaces of the molten resin with a gas. 6. A molding apparatus for molding a plastic molded product according to claim 1, wherein at least one non-transfer surface of said mold is a non-transfer surface of a molten resin. And a gas supply means for supplying a gas adjusted to a predetermined pressure and temperature toward the molding apparatus. 7. The gas supply means is formed in a mold portion having a non-transfer surface, and has one end opening into the cavity, the gas supply means being connected to the other end of the ventilation hole, and passing through the ventilation hole. 7. A molding device for plastic molded products according to claim 6, further comprising a supply device for supplying a gas adjusted to a predetermined pressure and temperature into the cavity. 8. A molding apparatus for molding a plastic molded article according to claim 3, wherein at least one non-transfer surface of said mold is provided with cooling means for cooling the non-transfer surface of said mold. A molding device for a plastic molded product, characterized in that: