JPH0679752A - In-mold coating method and injection molding die for in-mold coating - Google Patents

Abstract

PURPOSE:To execute coating simply by a method wherein a primary cavity larger than the shape of a molded article is formed by primary clamping of a die, a coating material is injected after a molding material corresponding to the volume of the molded article is, secondary clamping is executed and the molded article is coated with the coating material. CONSTITUTION:A movable die 3 is clamped to a fixed die 2 and thereby a primary cavity C having a shape and a capacity larger than the shape and the volume of a molded article is formed. In this cavity C, a molten molding material corresponding to the volume of the molded article is filled up from an injection nozzle through a sprue 4. Thereafter a coating material is injected from a coating material injector 5 and made to stick on the surface of the unset molding material and a cavity surface, while it fills a space. Then, a secondary cavity C2 corresponding to the shape and the volume of the molded article S is formed by secondary clamping and the material is molded to be the molded article S. Accordingly, the whole surface of the molded article S is coated with the coating material and the coating can be performed simply by an injection molding die.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-mold coating method and an injection mold for in-mold coating.

[0002]

2. Description of the Related Art In recent years, there has been a tendency to adopt an in-mold coating method in which a molded product is coated during molding in response to automation of molding work. In this in-mold coating method, when the cavity is filled with molten resin, the resin shrinks as it cools and solidifies, creating a minute gap between the cavity surface of the mold and the resin. A coating material is injected at high pressure to coat a molded product, which is proposed by Klaus.

[0003]

However, in such an in-mold coating method, as a result of utilizing the minute gap generated by the shrinkage of the resin in the cavity, it is easily affected by the viscosity of the coating material, and Since the flow length is also short, there is a drawback that the object of coating is limited to a specific injection molded product.

The present invention has been made in view of the above problems, and provides an in-mold coating method capable of easily coating an injection-molded article without particularly limiting the object and its injection-molding method. It is to provide the mold.

[0005]

According to the in-mold coating method of the present invention, a fixed side mold and a movable side mold are primarily clamped to form a primary cavity having a shape volume larger than that of a molded product. After filling the primary cavity with the molten molding material in a volume corresponding to the volume of the molded article, injecting the coating material into the primary cavity,
It is characterized in that the movable side mold is subjected to secondary mold clamping to form a secondary cavity having a shape volume matching the shape volume of the molded product to form the molded product, thereby coating the molded product with a coating material. It is a thing.

The in-mold coating injection molding die of the present invention comprises a fixed side die and a movable side die which forms a cavity by clamping the fixed side die. On the mold and the movable mold, a mating surface that slightly inclines toward the mold opening / closing direction is formed over the end of the cavity, and the movable mold is separated from the mating surface of the fixed mold by the mating surface. And a state in which a primary cavity having a shape volume larger than that of the molded product is formed, and a state in which their mating surfaces are engaged to form a secondary cavity having a shape volume that matches the shape volume of the molded product. It is selectable, and one or more injection ports of the coating material are opened in at least one of the fixed side mold and the movable side mold so as to face the cavity.

Further, the injection molding die for in-mold coating of the present invention comprises a fixed-side die and a movable-side die for clamping the fixed-side die to form a cavity. The mold is composed of a moving-side mold plate and a seal plate that is biased to project relative to the moving-side mold plate.The seal plate projects from the moving-side mold plate and contacts the fixed-side mold. A state in which a primary cavity having a shape volume larger than the shape volume of the molded product is formed, and a state in which the moving-side mold plate moves from the primary cavity to form a secondary cavity having a shape volume matching the shape volume of the molded product. Further, at least one of the fixed-side mold and the movable-side mold faces the cavity, and one or a plurality of coating material injection ports are opened.

[0008]

[Function] The fixed side mold and the movable side mold are primary-clamped to form a primary cavity having a shape volume larger than that of the molded product, and a molten state having a volume corresponding to the volume of the molded product is formed in the primary cavity. Fill the molding material. Then, the coating material is injected into the gap formed between the primary cavity and the molding material filled in the cavity.
After that, the movable side mold is secondarily clamped with respect to the fixed side mold to form a secondary cavity having a shape volume matching the shape volume of the molded product, and shaped into the final shape of the molded product. At this time, the coating material injected into the gap formed between the cavity and the molten resin adheres to the molded product and covers the molded product.

As a result, the in-mold coating can be easily applied to the injection molded product.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an injection molding die 1 of the present invention. This die 1 is composed of a fixed side die 2 and a movable side die 3, and the movable side die 3 is It is movable by a hydraulic cylinder (not shown), so that the mold can be opened and closed. Then, the fixed-side mold 2 and the movable-side mold 3 are clamped by the mating surfaces 2a and 3a, which are slightly inclined toward the mold opening / closing direction, to clamp the fixed-side mold 2 and the movable-side mold 3. The cavities C are formed so as to extend to the ends of the cavities C. The cavity C communicates with the tip of an injection nozzle (not shown) via a sprue 4 formed on the stationary mold 3. Therefore, at the time of injection molding, the molten molding material injected from the injection nozzle fills the cavity C through the sprue 4.

By the way, the fixed mold 2 and the movable mold 3 are provided with coating material injecting machines 5 and 5 connected to a coating material supply pump (not shown).
The injection ports 5a, 5a are opened facing the cavity surface, respectively.

Next, the molding operation of this embodiment will be described. The movable side mold 3 is first clamped to the fixed side mold 2 to form a primary cavity C1 having a shape volume larger than the shape volume of the molded product. To do. In this case, the mating surface 3a of the movable mold 3 is separated from the mating surface 2a of the fixed mold 2. Then, the primary cavity C1 is filled with the molten molding material from the injection nozzle through the sprue 4 in a volume corresponding to the volume of the molded product (see FIG. 2). At this time, since the filled molding material does not fill the volume of the primary cavity C1, a gap is formed between the cavity surface of each mold 2 and 3 and the filled molding material. After that, if the coating material supply pump is operated to inject the coating material from the inlet 5a of the coating material injecting machine 5,
The coating material is the uncured molding material surface or the mold 2,3
While adhering to the cavity surface of, it spreads to every corner of the gap (see FIG. 3).

Next, when the movable side mold 3 is advanced to a position where it abuts against the fixed side mold 2 and the secondary mold is clamped, a mating surface 2a of the fixed side mold 2 and a mating surface 3a of the movable side mold 3 are formed. Engage to form the secondary cavity C2 that matches the shape volume of the molded product S, so that the uncured molding material is compressed and the molded product S corresponding to the secondary cavity C2 is molded (FIG. 4). reference). At this time, the entire surface of the molded product S is coated with the coating material, because the coating material adheres to the surface of the molded product S including the coating material attached to the cavity surfaces of the molds 2 and 3 and the coating material floating in the gaps. Will be done.

Further, the in-mold coating method of the present invention can be applied to the injection mold 11 as shown in FIGS. 5 and 6. The movable side mold 13 of the injection molding mold 11 is composed of a moving side mold plate 13A and a seal plate 13B which is relatively movable with respect to the moving side mold plate 13A. The seal plate 13B is Usually, it is projected from the moving side template 13A by the biasing force of the spring 14. Then, the seal plate 13B is attached to the moving-side template 1
When the fixed mold 12 is brought into contact with the fixed mold 12 in a state of protruding from 3A and the primary mold is clamped, the seal plate 13B surrounds the cavity surface of the fixed mold 12 and the movable mold plate 13A together with Primary cavity C with large shape volume
1 is formed (see FIG. 5).

Further, the seal plate 13B is used as the fixed mold 12.
When the moving-side mold plate 13A is advanced to the position where it abuts on the fixed-side mold 12 in the state of being in contact with the second mold, and the secondary mold is clamped, the molded product S is made to match the cavity surface of the fixed-side mold 12.
The secondary cavity C2 having a shape volume that matches the shape volume of the above is formed (see FIG. 6).

Next, the molding operation by the injection molding die 11 will be described. The movable die 13 is primarily clamped to the fixed die 12, and the seal plate 13 of the movable die 13 is clamped.
B is brought into contact with the fixed side mold 12 to form a primary cavity C1 having a shape volume larger than that of the molded product. Then, the primary cavity C1 is filled from the injection nozzle through the sprue 4 with the molten molding material in a volume corresponding to the volume of the molded product (see FIG. 5). At this time, since the filled molding material does not fill the volume of the primary cavity C1, a gap is formed between the cavity surface of each mold 12, 13 and the filled molding material. After that, when the coating material supply pump is operated to inject the coating material from the inlet 5a of the coating material injecting machine 5, the coating material is formed on the surface of the uncured molding material or the molds 12,
It adheres to the cavity surface of No. 3 and spreads to every corner of the gap.

Next, the movable side mold plate 13 of the movable side mold 13
When A is advanced and the secondary mold is clamped, the secondary cavity C2 that matches the shape volume of the molded product S is formed together with the cavity surface of the stationary-side mold 12, so that the uncured molding material is compressed and the secondary A molded product S corresponding to the cavity C2 is molded (see FIG. 6). At this time, the entire surface of the molded product S is covered with the coating material, because the coating material adheres to the surface of the molded product S including the coating material attached to the cavity surfaces of the molds 12 and 13 and the coating material floating in the gaps. Will be done.

The coating material used in such an in-mold coating method may be either a thermoplastic resin or a thermosetting resin, and a material compatible with the molding material may be selected. In addition to the paint, the coating material may be an antistatic agent, a primer, an antibacterial agent, or the like, and its form may be liquid or powder such as powder. When using a powder coating material, it is preferable to provide a suction port separately. Also,
When a thermosetting resin is used as the coating material, the mold surface may be heated to a high temperature to accelerate the curing.

The coating material injection structure uses a needle valve, a porous material such as sintered metal, or a slit formed by closely adhering a block to prevent infiltration of molten resin. However, it is not particularly limited as long as it allows the passage of the coating material.

[0021]

As described above, according to the present invention, the fixed side mold and the movable side mold are primary-clamped to form a primary cavity having a shape volume larger than that of the molded product. After filling the molten material with a volume equivalent to the volume of the molded product, inject the coating material into the primary cavity, and further clamp the movable mold to the secondary mold to match the shape volume of the molded product. By forming a secondary cavity of the shape volume to form the molded product, the coating material injected into the gap formed between the primary cavity and the molding material filled in the cavity adheres to the molded product. The surface of the molded product can be covered with the coating material, and the in-mold coating can be easily applied to the injection molded product.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an overall configuration of an injection molding die of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a molding process using the injection mold of FIG.

FIG. 3 is an enlarged cross-sectional view showing a molding process using the injection mold of FIG.

FIG. 4 is an enlarged cross-sectional view showing a molding process using the injection mold of FIG.

FIG. 5 is an enlarged cross-sectional view showing a molding process using another injection mold of the present invention.

6 is an enlarged cross-sectional view showing a molding process using the injection mold of FIG.

[Explanation of symbols]

 1,11 Injection molding die 2,12 Fixed side die 3,13 Movable side die 2a, 3a Mating surface 13A Moving side die plate 13B Seal plate 4 Sprue 5 Coating material injection machine 5a Injection port C cavity C1 Primary cavity C2 Secondary cavity S Molded product

Claims (3)

[Claims] 1. A fixed-side mold and a movable-side mold are primary-clamped to form a primary cavity having a shape volume larger than that of a molded article, and a molding material in a molten state is molded into the primary cavity. After filling the volume equivalent to the volume, the coating material is injected into the primary cavity, and the movable side mold is secondary clamped to form a secondary cavity with a shape volume that matches the shape volume of the molded product. An in-mold coating method, which comprises coating a coating material on a molded product by molding the molded product. 2. A fixed-side mold, and a movable-side mold that forms a cavity by clamping the fixed-side mold,
The fixed side mold and the movable side mold are formed with a mating surface slightly inclined toward the mold opening and closing direction toward the end of the cavity, and the movable side mold has a mating surface that is aligned with the fixed side mold. A state in which a primary cavity having a shape volume larger than the shape volume of the molded product is formed apart from the surface, and a mating surface thereof engages to form a secondary cavity having a shape volume matching the shape volume of the molded product. Injectable for in-mold coating, characterized in that one or a plurality of coating material injection ports are opened to face the cavity in at least one of the fixed side mold and the movable side mold. Molding die. 3. A fixed-side mold, and a movable-side mold that forms a cavity by clamping the fixed-side mold,
This movable side mold is composed of a moving side mold plate and a seal plate biased so as to project to the moving side mold plate, and the seal plate projects from the moving side mold plate and becomes a fixed side mold. A state where the primary cavities that are in contact with each other to form a shape volume larger than the shape volume of the molded product are formed, and the moving side template moves from this primary cavity to form a secondary cavity having a shape volume that matches the shape volume of the molded product. The in-mold coating is characterized in that at least one of the fixed-side mold and the movable-side mold faces the cavity, and one or a plurality of coating material injection ports are opened. Injection mold.