JP3050698B2 - Method for manufacturing resin molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for performing in-mold coating on the surface of a resin molded product to obtain a resin molded product having improved surface quality.

[0002]

2. Description of the Related Art The in-mold coating method is a method in which the surface of a resin molded product is coated in the same process as the molding of a molding resin. And conventionally, a method of injecting the coating material into the mold by completely opening the mold,
A method of injecting a coating material with a mold closed is known from Japanese Patent Publication No. 55-9291.
Japanese Patent Application Laid-Open No. 61-273921 discloses a method of injecting a coating material into a mold at a high pressure while the mold is being pressed.

[0003]

Problems to be Solved by the Invention Japanese Patent Publication No. 55-92
In the conventional examples described in JP-A-91-91 and JP-A-61-273921, all are methods in which a molding resin for forming a resin molded body is compression-molded, and a coating material is injected after a lapse of a predetermined time. However, it does not directly detect the cured state of a molding resin for forming a resin molded body. For this reason, there is a possibility that a poor filling of the coating material or a poor adhesion between the resin molded body and the coating layer may occur due to variations in the curing characteristics of the molding resin and variations in the molding conditions.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to eliminate coating material imperfections due to variations in curing properties of molding resins and variations in molding conditions. Another object of the present invention is to provide a method for producing a resin molded product that can eliminate poor adhesion between the resin molded product and the coating layer and improve the surface quality of the resin molded product.

[0005]

In order to solve the above-mentioned problems of the prior art and achieve the object of the present invention, the method for manufacturing a resin molded product of the present invention comprises a first molding die 1 and a first molding die 1. The space 3 is formed by the second mold 2 movable with respect to the mold 1
The molding resin 4a is compression-molded in the space 3 to form a resin molded body 4. Thereafter, a coating material 5a is injected into the surface of the resin molded body 4 and compression-molded again to form the coating layer 5. A molding method for forming, wherein the first
An ion viscosity sensor 6 for detecting the degree of curing of the resin molded body 4 is installed in the molding dies 1 and 2 of the molding resin 4 and the ion viscosity sensor 6 is used to form the molding resin 4a for forming the resin molded body 4. In the compression molding step, the coating material 5a is injected when a predetermined ion viscosity value is detected after passing through the bottom value.

[0006]

According to the method of the present invention as described above, the ion viscosity sensor 6 for detecting the degree of cure of the resin molded body 4 is installed in the first and second molding dies 1 and 2, In the compression molding process of the molding resin 4a for forming the resin molded body 4, the ion viscosity sensor 6 injects the molding resin 5a for forming the coating layer 5 when a predetermined ion viscosity value is detected after passing through the bottom value. By doing, the resin molding 4
The coating material 5a can be caused to flow in a state where the curing reaction of the molding resin 4a for forming the resin is constant, and the surface of the resin molded body 4 is not filled with the coating material 5a, and
In addition, molding can be performed while keeping the adhesion conditions constant.

[0007]

FIG. 1 is a schematic explanatory view of an example of a mold apparatus of the present invention, and FIGS. 2 to 7 show a manufacturing sequence of an embodiment of the present invention. The mold device is the first mold to be the lower mold.
And a second mold 2 serving as an upper mold. In the embodiment shown in the accompanying drawings, the first mold 1 is a fixed mold, and the second mold 2 is movable. A second molding die 2 by a cylinder device 7 such as a hydraulic cylinder.
Moves vertically. In the figure, 20 is a press ram, 21 is a pressure control valve, 22 is a pump, 23
Is a press pressure controller, and 24 is a mold displacement meter.
The first molding die 1 is provided with a molding resin injection port 8 so that a coating material 5a for forming the coating layer 5 can be injected from the molding resin injection port 8 by a coating material supply device 9 such as an injection cylinder. It has become. In the figure, 25 is a tank, 26 is a stroke detecting device of an injection cylinder, 27 is a flow control valve, 28 is a pressure control valve,
29 is a pump. An on-off valve 10 is provided at the molding resin inlet 8.
Is provided. The first molding die 1 or the second molding die 2 is provided with an ion viscosity sensor 6 for detecting the degree of curing of the resin molded body 4. In addition, as the ion viscosity sensor 6 for detecting the degree of cure of the resin molded body 4, for example, a "polymer cure test system" manufactured by Sentech Co., Ltd. can be used.

[0008] The production of the resin molded article A having the coating layer 5 on the surface of the resin molded body 4 using the above-described mold apparatus is performed as follows. That is, first, as shown in FIG. 2, the second molding die 2 is raised to form the space 3, and in this state, the resin molding 4
Is placed on the first molding die 1. Here, a fiber-reinforced thermosetting resin is used as the molding resin 4a, and a filler such as calcium carbonate or aluminum hydroxide, a curing agent, a fibrous reinforcing material such as glass fiber or carbon fiber, etc. Depending on the composition, a thickener, a colorant, and the like are blended, and are supplied on the first mold 1 as BMC (bulk molding compound) or SMC (sheet molding compound). Next, as shown in FIG. 3, the second molding die 2 is lowered and clamped, and the molding resin 4 a is compressed under pressure to form the resin molded body 4. The condition in this case is, for example, to adjust the temperature of the mold to 140 ° C., and to adjust the temperature to 100 kg / cm.
Apply the molding pressure of ² for about 5 minutes. In this case, the degree of cure of the resin molded body 4 is checked by the ion viscosity sensor 6, and after the ion viscosity once decreases and reaches the bottom, it rises again and reaches a predetermined value (about 10 (s / cm) ⁻¹ ). Fig. 4 when reached
And raise the second mold 2 by about 5 mm to open it,
At the same time, the opening / closing valve 10 is opened as shown in FIG. The coating material supply device 9 inserts approximately 500 mm from the molding resin inlet 8 into the gap between the surface of the resin molding 4 and the first molding die 1.
Inject cc. When the injection of the coating material 5a is completed in this way, the on-off valve 10 is closed as shown in FIG. 6 and recompression molding is performed. As an example of the conditions in this case, the coating material 5 a is recompressed for about 7 minutes at a molding pressure of about 45 kg / cm ² , whereby the coating material 5 a is caused to flow to the end of the resin molded body 4. Thereafter, as shown in FIG. 7, the second mold 2 is lifted to open the mold, and the resin molded product A is taken out in this state. In the embodiment shown in the attached drawings, an example of a bathtub is shown as the resin molded product A. As described above, a resin molded product A having the high gloss coating layer 5 was obtained. FIG. 8 is a graph showing the relationship between the press pressure and the time due to the movement of the second mold 2 in the above embodiment.

[0009] By the way, when experiments are performed by changing the injection timing of the coating material 5a variously, as shown in FIG. 9, when the mold temperature is 125 ° C., for example, the time from the start of molding to the start of injection is about 3 minutes. If there is, the coating material 5a penetrates into the resin molded body 4 because the resin molded body 4 is not yet sufficiently cured, resulting in poor flow. Also, when about 6 minutes or more, the adhesion between the resin molded body 4 and the coating layer 5 is caused. When the cross-cut test was not performed because the property was not sufficiently ensured, it was found that poor adhesion such as partial peeling occurred. Mold temperature 1
FIG. 9 also shows the results of experiments at 35 ° C. and 145 ° C.
Thus, it was found that a desired resin molded product A can be obtained by performing the injection when the ion viscosity is about 10 (s / cm) ^-1 . In FIG. 9, a, b, and c show the cases where the mold temperatures are 145 ° C., 135 ° C., and 125 ° C., respectively. In this case, the optimum ion viscosity value for injection differs depending on the type of molding material, molding conditions, and the like.

[0010]

According to the present invention, as described above, the first
An ion viscosity sensor for detecting the degree of curing of the resin molded body is installed in the molding die or the second molding die, and the ion viscosity sensor detects the bottom in the compression molding process of the molding resin for forming the resin molded body. After passing the value, by injecting the coating material when a predetermined ion viscosity value is detected, the degree of cure of the resin molded body can be reduced compared to the method of determining the injection timing using a timer, mold displacement, or a pressure sensor. Since the timing is directly detected and the timing is determined, it is possible to inject the coating material into the mold in a fixed curing state without being affected by the variation in the curing characteristics of the molding resin or the variation in the molding conditions. The surface of the molded body can be filled with the coating material without poor filling. It is capable of providing a molded article.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a molding die used in the production method of the present invention.

FIG. 2 is an explanatory view showing a manufacturing order of the present invention.

FIG. 3 is an explanatory view showing a manufacturing order of the above.

FIG. 4 is an explanatory view showing a manufacturing order according to the embodiment.

FIG. 5 is an explanatory view showing a manufacturing order according to the embodiment.

FIG. 6 is an explanatory view showing a manufacturing order of the above.

FIG. 7 is an explanatory view showing a manufacturing order of the above.

FIG. 8 is a graph showing the relationship between press pressure and time in the above.

FIG. 9 is a graph showing a relationship between logarithmic ion viscosity and time according to the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st shaping | molding die 2 2nd shaping | molding die 3 space 4 resin molding 4a molding resin 5 coating layer 5a coating material 6 ion viscosity sensor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FIB29L 9:00 (72) Inventor Yoshikazu Maki 5-8, Nishiobari-cho, Suita-shi, Osaka Inside the Japan Catalyst Resin Technology Laboratory ( 56) References JP-A-3-251414 (JP, A) JP-A-4-44823 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 43/00-43/58

Claims (1)

(57) [Claims] A space is provided by a first molding die and a second molding die movable with respect to the first molding die, and a molding resin is compression-molded in this space to form a resin molding. Forming a coating layer by injecting a coating material onto the surface of the resin molded article and then compressing and molding the coating material again, wherein the resin molded article is formed in a first molding die or a second molding die. An ion viscosity sensor for detecting the degree of cure is installed, and when the ion viscosity sensor detects a predetermined ion viscosity value after passing a bottom value in a compression molding process of a molding resin for forming a resin molded product. A method for producing a resin molded product, comprising: injecting a coating material in the method.