JPH0615675A - In-mold coating method for resin molded item - Google Patents

Abstract

PURPOSE:To surely remove flashes from a molded item and uniformly coat the surface with a coating material by a method wherein a resin is compression molded by upper and lower molds having taper parts fitted to each other on the peripheries thereof, the mold is slightly opened before the resin is completely cured, an inclusion of foreign particles is prevented by a gas flow, the flowable coating material is injected, and the mold is clamped for heating and curing the resin. CONSTITUTION:Slide fitting parts of an upper mold 3 and a lower mold 4 are tapered. A coating material injection member (nozzle) 5 is provided on approximately the center of the lower mold (fixed mold) 4. A molding material is set between the upper mold 3 and the lower mold 4. After the mold is clamped, the molding material is heated. Before the molding material is completely cured, the upper mold 3 is slightly raised for forming a space S between the tapers. Next, a compressed air is fed into a cavity by an air pump 8 for blowing off flashes and foreign particles existing between the half cured material and the lower mold 4 and in the space S. After that, a coating material is injected. At this time, it is preferable that the coating material is so injected as to effusively fill the space S. After the mold is again clamped, the material is heated to be cured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin for forming a resin molded product using a split mold and then injecting a fluid coating material into the mold to form a coating layer on one side of the molded product. The present invention relates to a method for coating a molded product in a mold.

[0002]

2. Description of the Related Art When molding a thermosetting resin bathtub or panel, a synthetic resin coating layer is sometimes formed on one side of the bathtub or panel, for example, on the inner side of a bathtub. For example, a method called an in-mold coating method is known. This method uses a pair of split molds (generally composed of a male mold and a female mold) consisting of a fixed mold and a movable mold, and a block-shaped or sheet-shaped resin molding material (such as BMC or SMC) between them. After arranging the molding material, the mold is clamped (compressed) and heated and pressed to form a resin molded product having a predetermined shape, and then a fluid coating material is provided between one surface of the resin molded product and the mold surface. It is composed of a process of injecting and coating the surface of the molded product. In addition to the advantage that molding and coating are performed in the same equipment and in a series of processes, the surface is beautifully coated and the resin molding has excellent smoothness. There is an advantage that the product can be obtained.

FIG. 5 conceptually shows the step of injecting the fluid coating material by the above method. Since the resin molded product 1 is generally manufactured by a thermosetting resin, its molding is accompanied by compression. Since heating is required, and thermosetting resin is generally used as the above coating material, it is necessary to cool the coating material to such an extent that curing does not proceed excessively in order to maintain fluidity. Mold temperature control is awkward. Further, when injecting the fluid coating material, a mold is used in which a surplus portion 2 is formed in a part of the peripheral edge portion 1a of the resin molded product 1, and a nozzle opened to face the surplus portion 2 is used. It is general to inject the fluid coating material from the above, but there is a problem that the coating material does not always reach the peripheral portion at a position far away from the extra portion 2 at all times. In order to deal with this, it is necessary to provide a plurality of extra thickness portions and dispose respective independent injection means, which leads to an increase in die cost, maintenance control of the apparatus, and deterioration of productivity.

Therefore, an improved device as disclosed in Japanese Patent Laid-Open No. 62-160216 has been proposed. According to this, an apparatus for supplying the coating material from the position of the substantially central portion on the back surface side of the resin molded product is disclosed. 6A and 6B are partial cross-sectional explanatory views showing the operation procedure of the apparatus, in which the upper mold 3 is a movable mold and the lower mold 4 is a fixed mold. A coating material injection means 5 is provided at the center of the lower mold 4, and this means 5 is composed of a casing 5a that internally houses a plug-shaped hole forming means 5b so as to be able to move forward and backward. ) Is disposed through a space 7 that suppresses heat invasion from the interior. At the time of molding the resin molded product 1, the hole forming means 5b is projected to make the coating material injecting means 5 in a state in which the nozzle is blocked, and the hole forming means 5 is formed.
By b, the molding material is compression-molded in a state where a through hole is formed in the resin molded product 1 from the back surface side (the upper side in the figure) of the resin molded product 1 [see (a) figure]. Next, as shown in FIG. 2B, the hole forming means 5b is retracted to the inner depth of the coating material injecting means 5, and the clamping pressure of the upper mold 3 is relaxed and raised to form the lower surface of the upper mold 3 and the molding. A space A is formed between the articles 1, and the fluid coating material 2 is injected into the space A by the coating material injection means 5 through the through holes of the resin molded article 1. Therefore, according to the above apparatus, the coating material can be injected from the back surface side of the resin molded product 1, so that the coated surface of the resin molded product 1 can be formed uniformly.

However, even when the above apparatus is used, when the upper mold 3 is slightly elevated, the resin molded product 1 adheres to and follows the upper mold 3 or when the fluid coating material 2 is injected. The upper surface 1 of the resin molded product 1 may be caused by the coating material 2 penetrating between the lower surface 1b of the resin molded product 1 and the upper surface 4a of the lower mold 4.
In some cases, a coating layer having a uniform thickness could not be formed on a.

Then, the method returns to the method of injecting the coating material from the surface side of the resin molded product 1, and the coating material 2 is injected without raising the upper die 3, that is, in a state in which the compression force by the upper die 3 is slightly lowered. A method has been devised in which the upper die 3 is pushed up by the injection pressure and the coating material is coated (hereinafter also referred to as resin coating or coating). However, it is relatively difficult to balance the compressive force of the upper mold 3 and the injection pressure of the coating material, and there are many unsolved problems in deburring when forming a molded product and uniformity of resin coating. .

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is capable of surely deburring a resin molded product without involving the above-mentioned drawbacks and a covering material. An object of the present invention is to provide a method for coating a resin molded product in a mold, which is capable of coating the entire surface of the resin molded product with a uniform thickness.

[0008]

According to the present invention, which has achieved the above object, a molding material is compression-molded using a mold having a sliding fitting portion with a taper, and the fitting of the mold is completed before curing is completed. Loosen to form a gap between at least one surface of the molded product and the mold surface facing it, and in the taper fitting portion, and a gas flow is formed in the mold through the gap to remove foreign matter. An in-mold coating method for a resin molded product, characterized in that the mixture is prevented, and then a fluid coating material is injected into the space between the molded product and the mold surface, and the mold is clamped again and cured under pressure. .

Further, in the present invention, a part of the fluid coating material injected into the above-mentioned void is leaked through the void of the taper fitting portion, and then the mold is clamped and pressure-cured to thereby obtain a resin. It is possible to fully spread the flowable coating material throughout the molding.

Further, in the present invention, after the injection of the fluid coating material is completed, the mold is clamped again for pressure curing, and the case where the fluid coating material is injected and the mold is clamped again for pressure curing. Since both cases are included, those who implement the present invention can freely use those methods.

[0011]

1, 2 and 3 are partial sectional explanatory views showing the concept of a typical apparatus for carrying out the method of the present invention, and FIG.
FIG. 7 is a conceptual diagram of a flowable coating material injection step drawn corresponding to FIG. 6. In the apparatus of this embodiment, the lower mold 4 is a fixed mold, the upper mold 3 is a movable mold, and the coating material injection means 5 (hereinafter may be simply referred to as an injection member 5) at the substantially central portion on the lower mold 4 side.
It is shown that the upper mold 3 is arranged on the contrary.
Can be changed to a fixed mold, the lower mold 4 can be changed to a movable mold, and the injection member 5 can be arranged substantially at the center of the upper mold 3.

According to FIG. 4, the injection member 5 is provided with a casing 5a having an open front end surface, and a hole forming means 5b which penetrates the casing 5a and is movable back and forth. At the time of pouring the coating material, the upper mold 3 rises and the molded product 1 follows the upper mold 3 and is lifted up to the lower part (lower mold 4
A space A is formed therebetween, and a space B is formed in the casing 5a by retreating downward of the hole forming means 5b.
If the fluid coating material is injected in that state, the coating material is filled on the surface side (between the upper surface 4a of the lower mold 4 and the lower surface 1a of the resin molded product 1), and the lower surface of the resin molded product 1 is filled. A resin molded product 1 that can form a uniform resin coat
Leaching to the upper side of the is completely prevented.

The method of the present invention will be described below in accordance with the operating procedure of the resin molding coating apparatus. First, in (1) of FIG. 1, a molding material such as BMC or SMC is set with the upper mold 3 and the lower mold 4 opened. In the figure, 6 is a fluid coating material injection pump, and 8 is an air pump.

Next, in (2) of FIG. 1, the upper mold 3 is gradually lowered to complete the mold clamping state in (3) of FIG.
The upper mold 3 and the lower mold 4 are heated to advance the curing reaction of the molding material. The curing reaction is stopped before complete curing, and the upper mold 3 is slightly raised. (4) of FIG. 2 is an explanatory view showing a main part in this mold open state. A taper is formed in the sliding fitting portion of the upper mold 3 and the lower mold 4, and the taper is 3a, 4 respectively.
Denote by a. A space S is formed between the taper 3a and the taper 4a, and then, in (5) of FIG. 2, compressed air is blown out from the air pump 8 and the space between the semi-cured molded product and the lower mold 4 and the space S. An air flow is formed in the space, and molding burrs and dust existing in the space are blown out of the mold. Then Figure 2
The fluid coating material is injected as shown in (6) and (7). At this time, if a sufficient amount of the coating material is injected so as to overflow from the space S as shown in (7), dust in each space can be completely washed away and resin coating can be applied to every corner of the molded product. it can.

Next, the mold is clamped as shown in FIGS. (9) is an explanatory view showing a main part, and a resin coating is applied to every corner of the molded product. FIG. 3 (10) shows a state in which pressure heating is performed again, and in FIG. 3 (11), the mold is opened and the molded product is taken out of the mold.

The present invention is carried out as described above, but when the mold is re-clamped after the injection of the fluid coating material is finished, when the fluid coating material having a short gel time is selected, the fluidity is improved. It is also possible to perform mold clamping again while injecting the coating material, and in this case, the molding cycle can be significantly shortened and the productivity can be improved.

[0017]

EFFECTS OF THE INVENTION Since the present invention is constituted as described above, it becomes possible to uniformly and beautifully coat the entire surface of the resin molded product with the coating material.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing a procedure of a resin molding coating method according to the present invention.

FIG. 2 is an explanatory sectional view showing a procedure of a resin molding coating method according to the present invention.

FIG. 3 is a cross-sectional explanatory view showing a procedure of a resin molding coating method according to the present invention.

FIG. 4 is an explanatory cross-sectional view of a main part of an apparatus used in the resin molding coating method according to the present invention.

FIG. 5 is a schematic explanatory view showing the concept of a conventional resin molding coating.

FIG. 6 is a cross-sectional explanatory view of a main part of an apparatus used in a conventional resin molding coating method.

[Explanation of symbols]

 1 resin molded product 2 surplus part 3 upper mold 4 lower mold 5 coating material injection means

Front Page Continuation (72) Inventor Yoshikazu Maki 5-8 Nishiomitabicho Suita City Osaka Prefecture

Claims (4)

[Claims] 1. A molded product is compression-molded using a mold in which a taper fitting portion is formed at the outer peripheral position of the mold and at a sliding position, and the fitting of the mold is loosened before the completion of curing to obtain a molded product. By forming a gap between at least one surface of the mold and a mold surface facing the one surface, and in the tapered fitting portion, and forming a gas flow in the mold toward the outer peripheral direction of the mold through the gap. A method for in-mold coating of a resin molded product, characterized in that foreign matter is prevented from being mixed in, and then a fluid coating material is injected into the above-mentioned space between the molded product and the mold surface, and the mold is clamped again and cured under pressure. . 2. The resin molded article according to claim 1, wherein a part of the fluid coating material injected into the gap is leaked through the gap of the taper fitting portion, and then the mold is clamped and pressure-cured. In-mold coating method. 3. After the injection of the fluid coating material is completed,
The method for coating a resin molded product in a mold according to claim 1 or 2, wherein the mold is clamped again and cured under pressure. 4. The in-mold coating method for a resin molded product according to claim 1, wherein the fluid mold coating material is injected and the mold is clamped again to be pressure-cured.