JPH06297485A - Manufacture of plastic skin material - Google Patents

Abstract

PURPOSE:To shorten time required for heating a mold by heating the mold by induction heating, adhering resin powder to a molding surface of the heated mold, then emitting a microwave to a surface of the powder at an opposite side to a contact surface with the mold to heat the powder, and melting and solidifying it. CONSTITUTION:A mold 4 is inserted into a coil 5, an AC current is applied from a high frequency power source connected to the coil 5 to generate an alternating magnetic field at the coil 5. Then, the mold 4 is removed from the coil 5, and powdering is conducted. In this case, resin powder 8 in contact with a molding surface 4a of the mold 4 is melted by heat incorporated in the mold 4, and the powder 8 is adhered in a layer state along the surface 4a. Then, the mold 4 is introduced into a microwave heating unit, a microwave is emitted from a back surface side of a resin powder layer for about 30 sec, thereby melting and solidifying the resin powder layer. Thus, since a cycle time from heating of the mold to removing from the mold can be shortened, a decrease in power consumption can be performed.

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 plastic skin material used as a skin material for automobile interior materials such as instrument panels.

[0002]

2. Description of the Related Art As a skin material such as an instrument panel for a vehicle, a plastic skin material is generally used because it can be easily molded. This plastic skin material is often manufactured by a powder slush molding method, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-235612, because even if it has a complicated shape, it can be easily obtained. .

In this powder slush molding method, first, a powder made of, for example, a soft vinyl chloride resin is put in a heated mold, and resin powder is adhered in a layer form along the molding surface of the mold, and then the mold is moved. Powdering is performed by rotating 180 degrees to remove the resin powder that has not adhered. A heat medium circulation pipe is disposed outside the mold, and heat is conducted from the pipe to the mold by heating a heat medium having a predetermined temperature flowing through the pipe to perform heating. As a result, the contact surface of the resin powder with the mold is melted and solidified by the heat retained by the mold.

Next, when the surface of the resin powder which is not in contact with the molding surface of the mold is heated by radiant heat using a heater or the like, the heated surface of the resin powder is melted and a plastic film is formed. Then, by cooling the mold and removing the formed film from the mold, a plastic skin material having a desired shape can be obtained.

As a method of heating the mold or the resin powder, it is possible to use, for example, a convection method in which hot air is circulated, in addition to the above-mentioned heat conduction or radiant heat.

[0006]

However, all of the heating methods utilizing conduction, radiation, or convection used in the above-described manufacturing method are external heating methods, so that the mold,
Alternatively, since heating the resin powder has poor thermal efficiency and large heat loss, there is a problem in that it takes a relatively long time to raise the temperature and power consumption increases.

Further, when the resin powder is heated to be melted and solidified, the contact surface of the resin powder with the mold is melted and solidified by the heat retained in the mold which has been heated in advance.
It is not necessary to heat the mold any more, but in the conventional heating method, since the mold is also heated at the same time as the heating of the resin powder, the thermal efficiency is further deteriorated and the heating time becomes longer. It is one.

Further, as described above, if the heating time becomes long, the cycle time from the start of heating the mold to powdering, melting and solidifying, cooling, and demolding becomes long, so that the plastic skin material is mass-produced. However, there is a problem in that the manufacturing cost is high.

That is, in the case of mass-producing plastic skin materials, if the cycle time becomes long, the number of molds to be used will inevitably increase. However, the molds used in the powder slush molding method are electroformed. Since it takes a lot of time to manufacture and it is expensive, if the number of molds used is increased for the purpose of improving productivity, the cost of the plastic skin material will increase.

[0010]

In order to solve the above-mentioned problems, a method for producing a plastic skin material of the present invention comprises a resin powder adhered in layers along the molding surface of a mold for molding a plastic skin material. In a method for producing a plastic skin material in which a body is heated and melted, the mold is heated by induction heating, and resin powder is attached to a molding surface of the heated mold, and then the mold in the resin powder is used. The resin powder is heated and melted and solidified by irradiating a microwave from a surface opposite to the contact surface.

[0011]

As described above, when the mold for molding the plastic skin material is heated by utilizing the electromagnetic induction effect by the induction heating, the mold itself generates heat, and the heating is performed from the inside. Therefore, compared with the case of heating the mold from the outside by utilizing radiant heat, heat conduction, convection of hot air, etc., the induction heating has good thermal efficiency and less heat loss, and therefore the time required for heating the mold Can be shortened.

When the resin powder attached to the mold is irradiated with microwaves, frictional heat is generated in the resin powder, so that the resin powder is heated from the inside. Further, since the mold heated by induction heating is made of metal and reflects microwaves, the mold is not heated by the microwaves when the resin powder is melted and solidified. That is, since the heating by the microwave used for melting and solidifying the resin powder is internal heating and does not heat the mold, the thermal efficiency is good and the heat loss is small. It is possible to shorten the time required for solidification.

As described above, when the time required for heating the mold and melting and solidifying the resin powder can be shortened, not only the power consumption is reduced, but also the mold is removed from the start of heating. The cycle time to reach can be greatly shortened. Therefore, when mass-producing the plastic skin material, the productivity can be improved without using many molds having high manufacturing costs, and thus the cost of the plastic skin material can be reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS.

In this embodiment, as shown in FIG.
A case where a plastic skin material is manufactured as a skin material of the instrument panel 20 provided in the front of the vehicle interior as an interior material of the automobile will be described as an example.

As shown in FIG. 1B, the instrument panel 20 has a cushion layer 2 made of urethane resin, for example, on the upper surface of the core material 1. Then, on the upper surface of the cushion layer 2, as shown in FIG.
For example, a plastic skin material 3 made of PVC (polyvinyl chloride) is provided. The plastic skin material 3 is manufactured by the powder slush molding method because it can be easily molded as a skin material of an instrument panel 20 having a complicated shape.

In this powder slush molding method, as shown in FIG.
As shown in (a) and (b), a mold 4 made of Ni and having a thickness of about 2 to 4 mm is used. The mold 4 is manufactured by electroforming according to the shape of the instrument panel to be manufactured. If fine irregularities are formed in advance on the molding surface 4a of the mold 4, the irregular shape of the molding surface 4a is transferred to the plastic skin material as a texture pattern or stitches at the time of molding, and the patterned plastic material is formed. It becomes possible to form a skin material. In the present embodiment, the heating of the mold 4 is performed by induction heating utilizing an electromagnetic induction action, as described later, so that the material of the mold 4 is Ni if it is a magnetic substance. Besides, for example, Fe, Co or alloys thereof may be used.

Next, a method for manufacturing a plastic skin material by the mold 4 will be described step by step. First, Fig. 1
As shown in (a) and (b), the cross section is 10 mm x 20 m.
The mold 4 is inserted into a coil 5 formed by a rectangular copper pipe of m, and an alternating current is applied from a high frequency power source (not shown) connected to the coil 5 to generate an alternating magnetic field in the coil 5. As a result, an induction current is induced in the mold 4 made of Ni, which is a ferromagnetic material, by an electromagnetic induction action, and an eddy current loss and a hysteresis loss occur, and the mold 4 is heated. Then, if this state is maintained for about 30 seconds, the mold 4 is heated to 210 ° C to 260 ° C.

Then, the mold 4 is taken out from the coil 5 and powdered. In the powdering step, first, as shown in FIG. 2, the powder pox 7 is placed on the mold 4, and the resin powder 8 made of, for example, PVC contained in the powder box 7 is placed in the mold 4. Transfer. At this time, since the mold 4 is induction-heated as described above, the heat retained by the mold 4 melts the resin powder 8 which comes into contact with the molding surface 4a of the mold 4 and the molding surface 4a. The resin powder 8 adheres in a layered manner along.

Then, the mold 4 and the powder box 7 are rotated 180 degrees as shown in FIG. 3, and the mold 5 is placed on the powder pox 7, so that the surplus not attached to the mold 4 is removed. The resin powder 8 is stored in the powder box 7 again. As a result, a resin powder layer 6 that adheres along the molding surface 4 a of the mold 4 due to the heat retained by the mold 4 is formed in the mold 4. Assuming that the contact surface of the resin powder layer 6 with the die 4 is the surface, in this state, the surface of the resin powder layer 6 is melted by the heat retained by the die 4 and solidified. . However, the resin powder layer 6 as a whole is in a state of not being completely melted as it approaches the back surface side which is the side opposite to the contact surface with the mold 4.

Next, as shown in FIG. 4, the mold 4 is placed in the microwave heating device 10 and irradiated with the microwave 11 from the back side of the resin powder layer 6 for about 30 seconds.
The resin powder layer 6 is melted and solidified. The microwave heating device 10 is equipped with a magnetron 9 that radiates a microwave of 2.45 GHz. When the resin powder layer 6 is irradiated with microwaves 11, the molecules in the resin powder layer 6 vibrate, and the friction heat generated by this vibration heats and melts the resin powder layer 6 to solidify it, for example, a film. It becomes a plastic layer having a thickness of about 1 to 7 mm.

Since the microwave is reflected by the metal, the mold 4 does not generate heat in the microwave heating device 10. That is, since the surface side of the resin powder layer 6 is solidified before the microwave irradiation by the heat retained by the mold 4, it is not necessary to heat the mold 4 here. Therefore, the mold 4 is not heated by the irradiation of the microwave 11,
Only the resin powder layer 6 can be efficiently heated and melted.

After that, as shown in FIG. 5, the mold 4 is placed in a cooling device 14, and a cold water shower 12 jetted from a nozzle 13 is applied for a predetermined time to form a mold having a plastic layer 15 formed thereon. Cool 4. In addition to the above, as a cooling method, a method using a water tank or the like can be used. After cooling the mold 4, the plastic layer 15 is removed from the mold 4 to obtain a plastic skin material.

As described above, according to the method of manufacturing the plastic skin material of this embodiment, the mold 4 is heated to a predetermined temperature by induction heating before the resin powder 8 is charged, and the resin powder 8 is made into a metal. After adhering to the mold 4, the resin powder layer 6 formed in the mold 4 is further heated and melted by using microwave to be solidified.

By the way, in the conventional method for manufacturing a plastic skin material in which hot air is circulated in the heating chamber to heat the mold and the resin powder, as shown in FIG.
It takes 3 minutes or more to heat the mold to 0 ° C or higher,
Furthermore, since it takes more than 1 minute to melt and solidify and cool the resin powder charged into the mold, the cycle time from the start of heating the mold to powdering, melting and solidification, cooling, and demolding Was about 6 minutes.

On the other hand, in the manufacturing method of the present embodiment, as shown in FIG. 8 (b), the temperature of the mold is increased by induction heating and the resin powder layer is melted and solidified by using microwaves. It takes only about 2 seconds, and the cooling time only takes less than 1 minute.
It becomes possible to shorten to minutes.

That is, since the induction heating and the heating by the microwave heat the mold and the resin powder layer adhered to the mold from the inside, respectively, the heat conduction, the radiant heat, or the hot air as in the prior art described above. As compared with the case of heating from the outside by utilizing, etc., the heat efficiency is good and the heat loss is small, so that the time required for heating can be shortened and the power consumption can be reduced.

Further, since only the resin powder layer 6 generates heat and the mold 4 does not generate heat during irradiation with microwaves, the mold 4 which does not need to be heated is heated by the resin powder layer 6. At the same time, the thermal efficiency is improved and the time required for heating is shortened as compared with the conventional method in which the temperature is raised.

Furthermore, if the cycle time is shortened by shortening the heating time, the production of the plastic skin material can be performed without increasing the number of molds which are expensive to manufacture even when the plastic skin material is mass-produced. Since it is possible to improve the property, it is possible to reduce the cost.

Further, by applying the method for manufacturing a plastic skin material of this embodiment, as shown in FIG.
6 and the powder box 19 are connected by the rail 17, and the powder box 19 and the microwave heating device 10 are connected by the conveyor 21, so that a line for manufacturing the plastic skin material can be constructed. In this case, the mold 4 that is induction-heated by applying an alternating current to the coil 5 from the high-frequency power source 18 provided in the induction heating device 16 is rail-transported above the powder box 19 to perform powdering, It is held by the mold holding member 22.

Then, when the mold 4 held by the mold holding member 22 and the powder box 19 are rotated by 180 degrees, the resin powder is put into the mold 4, and when the two are reversed again, there is an excess. The resin powder is returned from the mold 4 to the powder box 19. Next, invert the mold 4 again,
The mold 4 to which the resin powder adheres is conveyed to the microwave heating device 10 by conveyor, and the magnetron 9 connected to the high frequency power supply 23 irradiates the resin powder in the mold 4 with microwaves to generate the resin. Melt and solidify the powder.

After that, the plastic skin material is obtained by cooling and demolding in the same manner as described above. As described above, by utilizing the above-mentioned line and automating from the heating of the mold to the melting and solidification of the resin powder, it is possible to further improve the productivity.

[0033]

As described above, the method for producing a plastic skin material according to the present invention comprises heating the mold by induction heating, adhering the resin powder to the molding surface of the heated mold, and then applying the above resin powder. The resin powder is heated and melted and solidified by irradiating with microwaves from the surface of the body opposite to the contact surface with the mold.

Therefore, the cycle time from the heating of the mold to the demolding can be shortened, so that the power consumption can be reduced and the number of high-cost molds to be used does not increase. However, the productivity of the plastic skin material can be improved, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 shows a shape of a coil used when induction heating a mold in a method for manufacturing a plastic skin material according to an embodiment of the present invention, in which (a) is a front view,
(B) is an AA arrow line view.

FIG. 2 is a schematic diagram showing a state in which resin powder is transferred from a powder box to a mold inserted in the coil.

FIG. 3 is a schematic view showing a state where excess resin powder is transferred from the mold to a powder box.

FIG. 4 is a schematic view showing a microwave heating device for melting and solidifying a resin powder layer formed in the mold.

FIG. 5 is a schematic diagram showing a cooling device used for cooling the mold.

6 (a) is a schematic perspective view showing a vehicle compartment provided with an instrument panel having the plastic skin material, FIG. 6 (b) is a perspective view showing a partial cross section of the instrument panel, and FIG. 6 (c) is an instrument. It is a principal part sectional drawing of a ment panel.

7A and 7B are views showing the shape of the mold, wherein FIG. 7A is a perspective view and FIG. 7B is a view as seen from the arrow BB.

FIG. 8 (a) is a graph showing the relationship between time and mold temperature when a plastic skin material is manufactured by a conventional method,
(B) is a graph showing the relationship between time and mold temperature when a plastic skin material was produced by the method of the above-mentioned example.

FIG. 9 is a schematic diagram of a case where a line for producing a plastic skin material is configured by applying the method of the above embodiment.

[Explanation of symbols]

 3 Plastic skin material 4 Mold 8 Resin powder 11 Microwave

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Claims (1)

[Claims] 1. A method for producing a plastic skin material, wherein resin powder adhered in layers along a molding surface of a plastic skin material molding die is heated and melted, wherein the die is heated by induction heating. After heating the resin powder on the molding surface of the heated mold, the resin powder is heated by irradiating microwaves from the surface of the resin powder opposite to the contact surface with the mold. 1. A method for producing a plastic skin material, which comprises melting and solidifying by melting.