JPH0357456Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is an improvement of an in-mold coating device, more specifically, a paint injection device used when painting synthetic resin molded products by the in-mold coating method. Regarding.

[Prior Art] As is well known, synthetic resin molded products, particularly sheet molding compound (SMC) molded products made from fiber reinforced synthetic resin (FRP), are conventionally In addition to being able to reduce the weight of the car body compared to those made of steel plates,
It has great practical merits in that it can improve product quality, such as improved appearance.

However, when painting the surface of this SMC molded product to finish it into a final product, the surface and vicinity of the molded product may be damaged by the air originally contained in the FRP material or the air that is drawn in when the FRP material flows during molding. The air bubbles that form are internal, and the air in these bubbles breaks the paint film during the drying process after painting and is released from the surface. With normal painting methods, pinholes occur in the paint film, making it difficult to maintain good quality. There is a problem that surface quality cannot be obtained.

As a countermeasure to this problem of pinholes, the FRP material is defoamed before molding to remove the air contained therein, and then SMC molding is carried out, but in reality the air contained in it is completely removed. There is also the problem that it is difficult to remove the air during molding, and that it is impossible to deal with the air that is drawn in during molding.

In addition, a vacuum forming method has been proposed that prevents air bubbles from remaining on and near the surface of the molded product by keeping the inside of the mold in a vacuum state during SMC molding. Since it is difficult to ensure the durability of the sealing member that maintains the vacuum in the mold, it is necessary to maintain the vacuum level of the space inside the mold stably and completely remove air bubbles on the surface of the molded product. was difficult. Furthermore, in the case of this vacuum forming method, internal air bubbles that were originally located in the relatively central part of the molded product and did not affect the surface quality tend to be drawn out to the surface of the molded product, and countermeasures must be taken to prevent these air bubbles. There was a problem with becoming.

Therefore, conventionally, after performing SMC molding,
With the molded product still in the mold, paint is injected onto the surface of the molded product inside the mold using a paint injection device, and the pressure applied from the mold fills the air bubbles on and near the surface. A so-called in-mold coating method has been proposed in which paint is filled to prevent pinholes from forming.

By the way, in the SMC molding method, upper and lower molds are heated to a predetermined temperature, and the FRP material is pressurized by the heated molds to hot-press mold the molded product. The in-mold coating method described above coats the surface of the molded product with a thermosetting paint within the mold.
The above-mentioned mold pressurizes the paint film to prevent the formation of pinholes, and the heat retained in the mold is used to efficiently dry and harden the paint in a short time. In-mold coating equipment uses in-mold coating paint (IMC paint)
In-mold coat injector (IMC) is installed inside the mold to inject into the space inside the mold.
The heat of the mold is transferred to the paint inside the injector,
As a result, the curing reaction of the paint progresses, resulting in the generation of pre-gel, a decrease in flow performance due to the progress of curing, and peeling of the paint film, making it difficult to consistently maintain excellent surface quality.

For this problem, for example,
In the publication, in an in-mold coating device in which an IMC injector is attached to a mold, a cooling chamber is provided around the outer periphery of a paint chamber that houses a pin-shaped valve body.
It has been proposed to cool the paint in the paint chamber by passing cooling water through this cooling chamber to prevent the paint from curing before being poured.

[Problems to be solved by the invention] However, the above-mentioned conventional IMC injector does not have a means to measure and control the temperature of the injected paint. If the temperature is increased, the part of the molded product near the tip of the IMC nozzle will be cooled excessively compared to the molding temperature, resulting in molding defects. It has been difficult to maintain the temperature below the gelling temperature at which curing begins to prevent the generation of pregels and peeling of the coating, and to stably ensure the excellent surface quality of molded products.

[Purpose of the invention] This invention was made in order to solve the above problems. By providing a means to measure and control the temperature of IMC paint, it is possible to coat molded products without causing molding defects due to overcooling. An object of the present invention is to provide an in-mold coating device that can stably ensure excellent surface quality.

[Means for solving the problem] For this reason, this invention uses a sleeve having a paint injection port that opens on the surface side of the molded product in an in-mold coating device that coats the surface side of the molded product in the mold. , a shutter-off pin that is slidably inserted through the sleeve and opens and closes the paint inlet; a paint supply passage that communicates with the paint inlet via the paint supply opening that is opened and closed by the shutter-off pin; and the paint supply passage. An injector is provided with a jacket portion that is provided around the injector to circulate the cooling fluid, and a temperature sensor is provided in the paint supply passage near the paint supply port, and the injector is cooled by the output signal of the temperature sensor. A control means is provided for controlling the amount of cooling fluid supplied.

[Effects of the invention] According to this invention, in order to measure the temperature of the paint as close as possible to the molded product, a temperature sensor is provided in the paint supply passage near the paint supply port, and the output signal of this temperature sensor is used to measure the temperature of the paint as close as possible to the molded product. In order to cool the injector, a control means is provided to control the supply amount of cooling fluid that circulates around the jacket part, so that the temperature of the paint is always maintained below the gelling temperature and hardening of the paint is reliably prevented. At the same time, it is possible to prevent a portion of the molded product near the injector tip from being excessively cooled compared to the molding temperature. As a result, it is possible to prevent molding defects due to partial overcooling, prevent the occurrence of pre-gel, peeling of the paint film, etc., and stably ensure excellent surface quality of the coated surface of the molded product.

[Example] Hereinafter, an example of this invention will be described in detail based on the accompanying drawings.

As shown in Fig. 2, a press device for hot pressing an FRP material to form an SMC molded product W includes a press platen 5 that is vertically movable.
2, a stationary lower mold 54 combined with the upper mold 53, and a press bolster 55 to which the lower mold 54 is attached. An IMC injector 1 for injecting IMC paint onto the surface of the SMC molded product W is attached to the upper mold 53 from the side, and the paint is stored in a paint tank 56.
A metering pump 57 is provided to pressurize and send a fixed amount of IMC paint to the IMC injector 1.

As shown in detail in FIG. 1, the IMC injector 1 is fitted into a multi-stage cylindrical chamber formed on the side surface of an upper die 53, and the rear part thereof is connected to a hollow cylindrical injector body 2. It is fixed to the upper die 53 via a fixing flange 3 fixed to the outer circumference. The injector main body 2 has
The main body 2 is inserted in the axial direction, and the tip thereof is inserted into the upper mold 5.
A sleeve 4 reaching the molding surface 53a of No. 3 is provided,
As will be described in detail later, IMC paint is applied to the through hole 4a provided in the axial center of the sleeve 4.
A shutter-off pin 5 for injection onto the surface of the molded product W is slidably inserted. The rear end of the shaft-off pin 5 is fixed to a connecting member 8 fixed to a piston 7 of a hydraulic cylinder 6.
The hydraulic cylinder 6 is arranged so that the reciprocating direction of the piston 7 is parallel to the sliding direction of the shutter-off pin 5, and the piston 7 reciprocates in synchronization with the opening and closing timing of the upper die 53.

Inside the main body 2, the IMC paint supplied from the metering pump 57 is applied to the top mold 5 at the tip of the sleeve 4.
A paint supply passage 9 is disposed parallel to the sleeve 4 in order to supply the paint to the paint inlet 4b opened inside the main body 2.
The paint supply port 9a is communicated with the through hole 4a of the sleeve 4 near the tip thereof. Inside the paint supply passage 9, a temperature sensor 11 having a temperature measuring contact 11a at the tip of the supply passage 9 is disposed,
The temperature sensor 11 is connected to a terminal head 12 mounted at the rear end of the paint supply passage 9. In order to measure the temperature of the paint as close as possible to the SMC molded product W, the temperature measuring contact 11a is located at the most extreme end of the paint supply passage 9, that is, near the paint supply port 9a.

Inside the main body 2, a sleeve 4 and a paint supply passage 9 are provided.
A cooling water supply pipe 14 and a cooling water discharge pipe 15 are connected to a water jacket 13 formed around the paint, so that cooling water can be circulated to keep the temperature of the paint below the gelling temperature. . A diaphragm type control valve 16 is installed on the upstream side of the cooling water supply pipe 14 to adjust the amount of cooling water supplied, and the control valve 16 receives a temperature signal from the temperature sensor 11 via the terminal head 12. The degree of opening is controlled by a temperature controller 17 which receives and adjusts the supply amount of cooling water according to the temperature of the paint at the temperature measuring contact 11a.

Preferably, the outer periphery of the main body 2 is provided with a structure that minimizes heat transfer from the upper mold 53 to the injector 1 between the outer peripheral surfaces of the main body 2 and the sleeve 4 and the inner surface of the chamber of the upper mold 53. In order to stabilize the temperature inside the main body 2 as much as possible, an air jacket 18 is provided for circulating cooling air.
An air supply pipe 19 and an air discharge pipe 21 are connected to the air jacket 18 via a fixed flange 3 forming a rear end thereof.

The operation of the in-mold coating apparatus configured as described above will be explained below.

The SMC molded product W obtained by hot press molding a plate-shaped FRP material using a press machine can use, for example, the following composition as the base FRP material.

a Base material: unsaturated polyester resin 80% b Low shrinkage agent: saturated polyester resin 20% *: 100 parts by weight of a and b above.

c Catalyst (curing accelerator): TBP (tertiary butyl perbenzoate), 0.1 part by weight per 100 parts by weight of a and b above.

d Stabilizer: PBQ (Pervesozoquinone) 0.1 part by weight per 100 parts by weight of a and b above.

e Filler: Calcium carbonate 180 parts by weight per 100 parts by weight of a and b above.

f Thickener: Magnesium oxide 1 part by weight per 100 parts by weight of a and b above.

g Crosslinking agent: styrene 5 parts by weight per 100 parts by weight of a and b above.

h Reinforcement agent: glass fiber 28 parts by weight per 100 parts by weight of a and b above.

After molding, the SMC molded product W is coated as a primer treatment by the in-mold coating method while being placed on the molding surface of the lower mold 54 according to the following procedure.

The upper die 53 of the press device is closed to hot-press mold the material, and then opened to coat the surface of the molded product W with the IMC paint and lifted slightly upward. At this time, the temperatures of the upper die 53 and the lower die 54 are maintained at a temperature suitable for hot press molding the material, for example, 140°C to 150°C.

In synchronization with the timing of the opening operation of the upper mold 53, the piston 7 moves to the left, and accordingly, the shutter-off pin 5 also moves to the left. At this time, shut off pin 5
The amount of movement of the piston 7 is set so that the tip thereof is located to the left of the paint supply port 9a and completely opens the paint supply port 9a. As a result, a certain amount of thermosetting IMC paint pressurized and fed by the metering pump 57 flows into the through hole 4a of the sleeve 4 from the paint supply port 9a via the paint supply passage 9. Molding surface 53a of upper mold 53 from paint injection port 4b
The gap 22 between the molded product W and the surface of the molded product W is filled.
During this time, the shut-off pin 5 is repeatedly moved back and forth by the piston 7 to help fill the paint.

When a predetermined amount of paint has been filled into the gap 22, the shutter-off pin 5 moves to the right to close the paint supply port 9a, and its tip reaches a position where there is no difference in level from the upper molding surface 53a. completely close the paint inlet 4b.

Thereafter, the upper mold 53 performs the closing operation again, pressurizes the paint filled in the gap 22, and fills the surface of the molded product W and the air bubbles near the surface with the paint, thereby creating pinholes on the paint film surface. The thermosetting paint is dried and cured in a short time by the heat retained in the upper and lower molds 53 and 54.

By the way, the IMC injector 1 according to this embodiment maintains the temperature of the paint filled in the gap 22 below the gelling temperature, and maintains the temperature of the paint filled in the gap 22 at a temperature so high that the portion of the molded product W near the tip of the injector 1 causes molding defects. A control means is provided for controlling the amount of cooling water flowing through the water jacket 13 to prevent excessive cooling. The means for controlling the amount of cooling water will be explained below.

In order to measure the temperature of the paint as close as possible to the molded product W, the temperature signal from the temperature measuring junction 11a placed in the paint supply passage 9 near the paint supply port 9a is sent to the temperature controller via the terminal head 12. 17. The temperature controller 17 controls the cooling water supply pipe 1 according to the temperature signal.
A control signal is sent to a control valve 16 provided at 4 to adjust the amount of cooling water. That is, if the paint temperature is lower than the predetermined set temperature, the control valve 16
The valve opening of the control valve 16 is decreased to reduce the amount of cooling water to raise the paint temperature, and if the paint temperature is higher than the set temperature, the valve opening of the control valve 16 is increased to increase the amount of cooling water to lower the paint temperature. , the paint temperature is controlled so that it always remains at the set temperature.

As described above, according to the embodiment of this invention, in order to measure the temperature of the paint at a location as close to the molded product W as possible in the injector of the in-mold coating device, the paint supply near the paint supply port 9a is A temperature sensor 11 having a temperature measuring contact point 11a is provided in the passage 9, and a control valve 16 controls the amount of cooling water circulating around the water jacket 13 to cool the injector 1 based on the output signal of the temperature sensor 11. Since the opening degree of the valve is controlled, the temperature of the paint is always maintained below the gelling temperature to reliably prevent the paint from curing, and the part of the molded product W near the tip of the injector 1 is kept at the molding temperature. It is possible to prevent excessive cooling compared to the above. As a result, it is possible to prevent molding defects due to partial overcooling, prevent the occurrence of pre-gel and peeling of the paint film, and stably maintain excellent surface quality of the coated surface of the molded product.

[Brief explanation of the drawing]

Both Figures 1 and 2 are for explaining an embodiment of the present invention. Figure 1 is a configuration diagram of an in-mold coating apparatus including a vertical cross-sectional view of an injector, and Figure 2 is a diagram of an in-mold coating apparatus. including
FIG. 1 is an overall configuration diagram of a press device that performs SMC molding. 1...Injector, 4...Sleeve, 4b...
...Paint inlet, 5...Shut-off pin, 9...
Paint supply passage, 9a...Paint supply port, 11...Temperature sensor, 11a...Temperature measuring contact, 13...Water jacket, 16...Control valve, 17...Temperature controller.

Claims (1)

[Scope of Claim for Utility Model Registration] An in-mold coating device for coating the surface side of a molded product in a mold, comprising: a sleeve having a paint inlet opening on the surface side of the molded product; and a sleeve that slidably passes through the sleeve. A shutter-off pin that opens and closes the paint injection port when inserted into the paint supply port, a paint supply passage that communicates with the paint injection port via the paint supply port that is opened and closed by the shutter-off pin, and a paint supply passage that is provided around the paint supply passage to supply cooling fluid. In addition to providing an injector having a jacket portion that circulates, a temperature sensor is provided in the paint supply passage near the paint supply port, and an output signal of the temperature sensor controls the amount of cooling fluid supplied to cool the injector. An in-mold coating device characterized by being provided with a control means.