JPH0825438A - Production of thermoplastic resin molding - Google Patents

Abstract

PURPOSE:To prevent an apparatus from becoming extremely large scale even when a large thermoplastic resin molding is produced by molding a part having a good appearance or design surface by an injection molding method and molding other part by a press molding method. CONSTITUTION:A mold consists of male and female molds 1, 2. Resin supply ports 3a, 3b opened to the molding surfaces of a mold region having to perform press molding and a mold region having to perform injection molding are provided to the male mold at least by one with respect to the respective regions so as to be independently subjected to opening and closing control. The number of the resin supply ports is appropriately determined corresponding to the sizes of the respective regions or the shape of a molded object. The resin supply ports may be branched from the resin passage provided to the mold to be connected or may be connected to independently provided resin passages 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic resin molding.

[0002]

2. Description of the Related Art Thermoplastic resin moldings are widely used in automobile interior parts (for example, door trims, rear trims, instrument panels), interior / exterior parts of home electric appliances and other wide fields. Injection molding methods and press molding methods are known as typical body manufacturing methods.

However, in the case of the former injection molding method, although the cavity surface can be transferred well and a molded article having an excellent appearance can be obtained, since the molten resin is pressed into the entire sealed cavity, There is a problem that a large pressurization force that can withstand the pressure input is required and the apparatus becomes large in size, and it becomes very remarkable especially when the molded body becomes large. On the other hand, in the case of the latter press molding method, since the molten resin is supplied between the molds opened from the resin nozzle provided in the mold and the molten resin is spread by the mold clamping, the molding can be performed at a low pressure. However, there is a problem that uneven gloss and fine wrinkles called charge marks are likely to appear on the surface of the product near the resin supply port, and the appearance of the product is deteriorated.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The present inventors have earnestly studied a molding method that has the features of both the injection molding method and the press molding method, even when manufacturing a large-sized thermoplastic resin molded body, without requiring an extremely large scale of equipment. In a series of molding steps of a desired thermoplastic resin molded body, a good appearance is required, a part having a design surface is injection molded, and other parts are molded by a press molding method. A manufacturing method was developed and the present invention was achieved.

[0005]

The present invention relates to a method for producing a thermoplastic resin molded product by using a mold composed of a male and female pair of molds. 1) Supply to a press-molded portion between the opened male and female molds. Out of the total molten thermoplastic resin, the step of supplying the molten thermoplastic resin in an amount necessary to form the press-molded portion of the final molded body, 2) forming the injection-molded portion of the resin-unsupplyed portion Process of mold clamping until the mold space is sealed and the cavity clearance of the molten resin supply part reaches the final product thickness. 3) Retaining the cavity clearance while remaining in the resin mold unsealed mold space From the step of injecting and supplying the molten thermoplastic resin to fill the molten resin, 4) the step of cooling and solidifying the thermoplastic resin in the mold, and then opening the mold to take out the molded body. Heat There is provided a method for manufacturing a sexual resin molding.

The present invention also provides a manufacturing method as described above,
At the boundary between the press molding part and the injection molding part of the mold surface of either male or female mold, use a mold with a movable weir that slides inside the mold so that it can project into the cavity. Method of adding protrusion and storage of movable weir in front and back, that is, 1) opening both male and female molds and protruding movable weir into cavity, 2) supplying all over cavity surface in movable weir Of the molten thermoplastic resin, a step of supplying the molten thermoplastic resin in an amount necessary to form the press-molded portion in the final molded body, 3) a mold for forming the injection-molded portion of the resin-unsupplied portion Process of clamping the mold until the space is hermetically closed and the cavity clearance of the molten resin supply unit reaches the final product thickness, 4) step of storing the movable weir in the mold, 5) resin is not supplied while maintaining the cavity clearance Road A step of injecting and supplying the remaining molten thermoplastic resin into the closed mold space to fill the molten resin, 6) cooling and solidifying the thermoplastic resin in the mold, and then opening the mold The present invention provides a method for producing a thermoplastic resin molded body, which comprises a step of taking out the molded body by means of

The present invention will be described below with reference to the drawings.
In the following description, the open mold means that the mold is not closed until the cavity clearance between the male and female molds becomes the final product thickness. Further, this description is an example of the method of the present invention, and the present invention is not limited to this. FIG. 1 is a perspective view showing an example of a thermoplastic resin molded body obtained by the method of the present invention, and FIG. 2 is a vertical cross section taken along line XX of the molded body of FIG. Here, the part surrounded by the dotted line shown in FIG. 1 shows the molding part by the press molding method, and the remaining part is the molding part by the injection molding method. 3 to 6 are schematic sectional views of a mold showing the molding step in the manufacturing method of the present invention. Here, the mold is composed of a male and female pair of a male mold (1) and a female mold (2), and the male mold has metal molds of respective mold regions to be press-molded and injection-molded. At least one resin supply port (3) opening in the mold surface is provided in each region, and the opening and closing of each resin supply port can be controlled independently. The number of resin supply ports is appropriately determined depending on the size of each region, the shape of the molded body, and the like. Each resin supply port may be branched and connected from the resin passage (4) provided in the mold, or may be connected to the resin passage (4) independently provided.

Both male and female dies are placed in an open state such that the cavity clearance is equal to or more than the final product thickness,
The total amount of the molten thermoplastic resin (5) required to form the press-molded portion of the final molded body out of the total molten thermoplastic resin supplied to the mold surface of the portion where press molding is desired is made into a resin. The mold space for supplying the resin through the supply port (3) and then forming the injection-molded portion of the resin non-supplying portion is in a sealed state,
In addition, the mold is clamped until the cavity clearance of the molten resin supply section reaches the final product thickness. At this time, the mold may be clamped after supplying the required amount of molten resin, or the mold clamping may be started while supplying the molten resin, and the mold clamping may be performed at the same time when the supply of the required amount of molten resin is completed. The supply of the molten resin and the mold clamping may be performed at any time as long as the required amount of the molten resin has been supplied at the same time as or before the cavity clearance reaches the final product thickness.

When the mold clamping is completed, the male and female molds are kept under pressure to maintain the cavity clearance at the final product thickness,
According to the usual injection molding method, the residual molten thermoplastic resin is injected and supplied into the closed mold space of the resin non-supplying portion from the resin supply port opened on the mold surface forming the space, To fill. When the molten resin is injected and supplied, the holding when the cavity clearance is kept at the final product thickness does not have to be strict unless the cavity clearance becomes smaller than the final product thickness. For example, the molten resin is injected and supplied. At this time, the holding pressure of both molds may be loosened, or the molds may be slightly opened by the injection pressure of the resin, and the mold may be clamped again after the completion of the resin supply until the final product thickness is reached. Such an embodiment is also included. In the method of the present invention, different resins are used for supplying the resin to the press-molded portion and the resin to the injection-molded portion, or by supplying different resin from each resin supply port, two-color molding or more is achieved. It is also possible to perform multicolor molding. When the molding is completed, the molten thermoplastic resin is cooled and solidified in the mold, and then the mold is opened to take out the molded body.

The present invention also provides, in the above method,
In order to clearly distinguish the press-molded part and the injection-molded part of the obtained molded body and prevent the molten resin from flowing out to the injection-molded part during press-molding, the mold surface of either male or female mold A mold having a movable dam (6) that slides in the mold so as to project in the cavity is used at the boundary between the press molding part and the injection molding part. By adding the storage, it is possible to control the position where different molding methods of the press molding part and the injection molding part collide in the mold, and to manufacture a higher quality thermoplastic resin molded body.

FIGS. 7 to 10 are schematic sectional views of a mold showing an example of a molding process according to this manufacturing method. The mold used in this method is a movable weir that slides in the mold so that it can project into the cavity at the boundary between the press molding part and the injection molding part on the mold surface of either male or female mold. 6) is provided, and the movable weir is provided at the boundary between the press molding part and the injection molding part of the mold surface of either male or female mold, and can be projected into the cavity by the sliding device (7). It has a structure that slides in the mold in the opening / closing direction of the mold. The movable weir may be continuous or discontinuous at the boundary between the press molding portion and the injection molding portion of the mold surface. For example, the press molding portion as shown in FIG. In the case where the entire peripheral edge of the press-molded part is surrounded by the injection-molded part in the central part, it is preferable that the movable weir provided at the boundary part is a continuous body, and the end of the press-molded part is In the case where the portion is the end of the molded body, it may be provided only at the portion where the press-molded portion and the injection-molded portion are in contact with each other. Of course, continuous in this case is apparent, and structurally, it may be divided in a slidable length unit. The sliding distance of the movable weir in the mold opening / closing direction needs to be more than the final product thickness, but exceeding this distance and making it longer than necessary may make the mold thicker than necessary. However, the strength of the movable weir must be increased more than necessary, and normally the final product thickness is 15
It is not more than 10 times, preferably not more than 10 times.

In this method, the male and female molds are opened, the movable dam (6) provided in the male mold (1) is projected into the cavity more than the thickness of the final product, and then surrounded by the movable dam. An amount of molten thermoplastic resin (5) required to form a press-molded portion is supplied to the cavity surface from a resin supply port (3) opening in the cavity surface (Fig. 7), and a movable weir (6) is supplied.
While pressing down, lower the female mold (2) and clamp the mold until the cavity clearance reaches the final product thickness (Fig. 8). The mold clamping at this time may be started after supplying the molten resin, or the mold clamping is started while the movable dam is being pushed down while supplying the molten resin, and the mold clamping is completed at the same time when the supply of the required amount of the molten resin is completed. If the required amount of molten resin has been supplied at the same time as or before the cavity clearance reaches the final product thickness, the timing of the molten resin supply and the mold clamping does not matter.

After completion of the mold clamping, the movable weir (6) is retracted and housed in the male mold. At this time, it is necessary to make the tip of the movable weir to be a smooth surface in conformity with the cavity surface of the male mold. Unevenness occurs at the position corresponding to the movable weir.
After retreating the movable weir, in the same manner as above, the molten thermoplastic resin is injected and supplied into the remaining mold space (FIG. 9), and the mold space is filled to perform injection molding (FIG. 10). After the injection molding, the molten thermoplastic resin is cooled and solidified in the same manner as described above, and the molded body is taken out from the mold.

The thermoplastic resin used in the present invention is a resin usually used in press molding, injection molding, extrusion molding and the like, for example, polypropylene, polyethylene, acrylonitrile-styrene-butadiene block copolymer, polystyrene. , General polyamides such as polyamides such as nylon, polyvinyl chloride, polycarbonate, acrylic resins, styrene-butadiene block copolymers, thermoplastic elastomers such as EPM and EPDM, mixtures thereof, and polymers using these. Alloys and the like, which may be non-foaming or foaming. Further, these thermoplastic resins may contain a commonly used glass fiber, a filler such as various inorganic or organic fillers, if necessary, and of course, various pigments, lubricants, or the like which are usually used. Various additives such as an antistatic agent and a stabilizer may be blended.

[0015]

According to the manufacturing method of the present invention, even when a large-sized thermoplastic resin molded body is manufactured, since it can be carried out at a relatively low pressure, the apparatus does not require a large scale, and a predetermined molded body can be obtained. It is possible to obtain a molded product having a good surface appearance.

[0016]

The present invention will be described in more detail with reference to the following examples, but it goes without saying that the present invention is not limited thereto. In the following examples, a polypropylene resin (Sumitomo Noblen BPZ5077 manufactured by Sumitomo Chemical Co., Ltd.) was used as the thermoplastic resin.

Example 1 According to the steps shown in FIGS. 3 to 6, a male and female metal having a cavity surface designed to have a product shape whose appearance is shown in FIG. 1 and whose cross section is shown in FIG. Using a pair of molds, the wall thickness is 2.5 mm by the following method,
A thermoplastic resin multilayer molded body having a product shape shown in FIG. 1 having a length of 400 mm, a width of 550 mm, and a sidewall height of 10 mm was manufactured. In this example, the molten thermoplastic resin supplied is 200 ° C and the mold temperature is 40 ° C. A pair of male and female dies consisting of a female mold (2) that is a movable mold and a male mold (1) that is a fixed mold is opened, and a cavity clearance of 6 mm is passed through a resin passage (4). 250 g, which is 1.05 times the amount of resin required to form the press-molded portion from the resin supply port (3a)
The molten thermoplastic resin (5) is supplied. (FIG. 3) After supplying the molten thermoplastic resin, the resin supply port (3a) is closed, and the female mold (2) is lowered and clamped until the cavity clearance becomes 2.5 mm. (FIG. 4) While maintaining the mold clamping pressure so as to maintain this state, the resin supply port (5b) is opened, and 350 g of the remaining molten thermoplastic resin (5) is injected and supplied into the remaining mold space ( 5), the mold space is filled with resin. (FIG. 6) After cooling the mold and cooling and solidifying the supplied molten resin, the mold is opened and the molded body is taken out. The mold clamping force required for the molding at this time was 250 tons, and the appearance of the obtained molded product was found to have uneven gloss at the resin supply port portion of the press-molded portion, but a beautiful appearance is required. The injection-molded part had good gloss without unevenness over the entire surface.

Comparative Example 1 In the method of Example 1, 600 g of molten thermoplastic resin (5) was introduced from the resin supply port (3a) into the cavity without injection molding in the process and with a cavity clearance of 6 mm. The mold was clamped until the cavity clearance reached 2.5 mm. Then, it was cooled and solidified to obtain a molded product having the same shape as that of Example 1. The mold clamping force required for molding at this time was 150 tons, but in the obtained molded product, uneven gloss was observed in all resin supply port portions of the molded product.

Comparative Example 2 In the method of Example 1, the mold was clamped to a cavity clearance of 2.5 mm without performing the press molding in the process, and the resin supply port ( 600 g of molten thermoplastic resin (5) was injected and filled from 3a), and then the mixture was cooled and solidified to obtain a molded product having the same shape as that of Example 1.
The obtained molded product had a good gloss and no unevenness in gloss, but the pressing force was as high as 450 tons.

Example 2 According to the steps shown in FIGS. 7 to 10, both male and female metal having a cavity surface designed to have a product shape whose appearance is shown in FIG. 1 and whose cross section is shown in FIG. Using a pair of molds consisting of molds, a mold with a movable weir that slides inside the mold so that it can project into the cavity is used on the boundary surface between the male press molding part and the injection molding part. A thermoplastic resin molded product having the product shape shown in FIG. 1 was manufactured by the method described in 1. In this example, the thermoplastic resin to be used, the supply temperature of the thermoplastic resin, and the mold temperature are the same as in Example 1. A pair of male and female dies consisting of a female mold (2) that is a movable mold and a male mold (1) that is a fixed mold is opened, and a movable weir (6) provided in the male mold has a male cavity at the tip thereof. It protruded from the surface to 10 mm. The female mold was lowered while pushing down the movable weir, and was surrounded by the movable weir from the resin supply port (3a) via the resin passage (4) at a position where the cavity clearance between the male and female molds became 6 mm. To the cavity, 250 g of molten thermoplastic resin (5), which is 1.05 weight times the amount of resin required to form the press-molded portion surrounded by the movable weir, is supplied. (FIG. 7) After supplying the molten resin, the resin supply port (3a) is closed, and the female mold is further lowered while the movable dam is pushed down until the cavity clearance becomes 2.5 mm, and the mold is clamped. (FIG. 8) While maintaining this state, the movable weir is retracted until the tip thereof is flush with the cavity surface of the male mold, and is housed in the mold. While maintaining the mold clamping pressure so as to maintain this state, the resin supply port (3b) is opened, and 350 g of the remaining molten thermoplastic resin (5) is injected and supplied into the remaining mold space (FIG. 9). Fill the mold space with resin. (FIG. 10) After cooling the mold and cooling and solidifying the supplied molten resin, the mold is opened and the molded body is taken out. The mold clamping force required for the molding at this time was 250 tons, and the appearance of the obtained molded product was uneven in gloss at the resin supply port of the press-molded part, but a beautiful appearance is required. The injection-molded part had good gloss without unevenness over the entire surface.

[Brief description of drawings]

FIG. 1 is an external view of an example of a molded body manufactured by the method of the present invention.

FIG. 2 shows an X-X cross section of the molded body of FIG.

FIG. 3 is a schematic view of a mold cross section showing a manufacturing process of the present invention.

FIG. 4 is a schematic view of a mold cross section showing a manufacturing process of the present invention.

FIG. 5 is a schematic view of a mold cross section showing a manufacturing process of the present invention.

FIG. 6 is a schematic view of a mold cross section showing a manufacturing process of the present invention.

FIG. 7 is a schematic view of a mold cross section showing a manufacturing process when a movable weir of the present invention is used.

FIG. 8 is a schematic cross-sectional view of a mold showing a manufacturing process using a movable weir according to the present invention.

FIG. 9 is a schematic cross-sectional view of a mold showing a manufacturing process when a movable weir is used according to the present invention.

FIG. 10 is a schematic cross-sectional view of a mold showing a manufacturing process using a movable weir according to the present invention.

[Explanation of symbols]

 1: Male mold 2: Female mold 3: Resin supply port 4: Resin passage 5: Molten thermoplastic resin 6: Movable dam 7: Sliding device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Goto 2-10-1 Tsukahara, Takatsuki-shi, Osaka Sumitomo Chemical Co., Ltd.

Claims (2)

[Claims] 1. A method for producing a thermoplastic resin molded product by using a mold comprising a male and female pair, 1) the total amount of the molten thermoplastic resin supplied to the press-molded portion between the opened male and female molds. , The step of supplying the molten thermoplastic resin in an amount necessary to form the press-molded portion of the final molded body, 2) The mold space for forming the injection-molded portion of the resin non-supplying portion is in a closed state And, the step of clamping the mold until the cavity clearance of the molten resin supply section reaches the final product thickness. 3) While maintaining the cavity clearance, the residual molten thermoplastic resin is placed in the closed mold space of the resin non-supply section. The heat is characterized in that it comprises a step of injecting and supplying and filling a molten resin, 4) a step of cooling the thermoplastic resin in the mold and solidifying it, and then taking out the molded body with the mold opened. Made of plastic resin Form manufacturing method. 2. A method for producing a thermoplastic resin molding using a mold comprising a male and female mold, wherein a cavity is formed at the boundary between the press molding part and the injection molding part on the mold surface of either of the male and female molds. Using a mold provided with a movable weir that slides in the mold so that it can project, 1) opening both male and female molds and projecting the movable weir into the cavity, 2) cavity surface inside the movable weir Above, a step of supplying the molten thermoplastic resin in an amount necessary to form the press-molded portion of the final molded body out of the all molten thermoplastic resin to be supplied, 3) Injection molding of a portion not supplied with resin The mold space that forms the parts is sealed, and the mold is clamped until the cavity clearance of the molten resin supply part reaches the final product thickness, 4) the step of housing the movable weir in the mold, 5) maintaining the cavity clearance While not supplying resin The step of injecting and supplying the remaining molten thermoplastic resin into the sealed mold space to fill the molten resin, 6) Cooling and solidifying the thermoplastic resin in the mold, and then opening the mold The method for producing a thermoplastic resin molded article, comprising: