JPH10309731A - Mold for decorating molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease partial reduction of the thickness of a decorating sheet and to prevent deformation, discoloration, break and wrinkle of a printed pattern or the like by a method wherein a surface for clamping of the decorating sheet in a female mold is made to be outside from the edge part of the cavity of the female mold by a prescribed dimension and made to project toward the male mold side by a prescribed dimension from a mold open surface. SOLUTION: A female mold 1 is provided with a frame body 42 moved back and forth by an ejector device 41 and a decorating sheet S is clamped between the frame body 42 and a sheet clamping surface 12a of a frame-shaped body 12 provided on a mold open surface P of the female mold 1. This frame- shaped body 12 is so shaped as to conform to the edge part CE of the cavity of the female mold 1, being located outside from the edge part CE by a dimension A. The ratio A:B between the dimension A and the height of the frame- shaped body 12, i.e., a dimension B formed by the sheet clamping surface 12a and the mold open surface P of the female mold 1 is made 1:1-50:1. The dimension B is 1 mm or above preferably. At the time when the decorating sheet S is heated by a heating plate 5, as the result, an actual softened area is made large and also an effect of friction with the female mold 1 is lessened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called decorative used in a molding process of a decorative molded product using a decorative sheet (including a decorative film, hereinafter simply referred to as a decorative sheet). A molding die, and more specifically, a molding method in which a decorative sheet is insert-molded, or the decorative sheet is used as a transfer sheet and a printed portion applied to the sheet is transferred to a molded product surface. It relates to the mold used.

[0002]

2. Description of the Related Art There is known an in-mold molding method in which a decorative sheet is brought into close contact with a cavity surface in advance by injection molding to insert the decorative sheet into a surface portion of a molded product. 50-1
9132). In this molding method, generally, a decorative sheet such as a laminating sheet supplied between a female mold and a male mold in an open state is softened by heating, and then vacuum suction is applied to a cavity surface of the female mold. Such a method is adopted that a shape is formed so as to be in close contact by a technique such as that described above, and then the mold is clamped to supply a molten resin into the cavity.

[0003] In the above method, by using a transfer sheet as a decorating sheet, a transfer layer such as printing laminated on the transfer sheet can be transferred to the surface of a molded article.

In a conventional apparatus employing the above-described decorative molding method, specifically, as shown in a cross-sectional view of FIG. 5, a material is supplied between a female mold 501 and a male mold 502 in an open state. The decorated sheet S is clamped by being pressed against the mold opening surface P of the female mold 501 by the clamp mechanism 503, and the heating sheet 504 is brought close to the decorated sheet S, thereby heating the decorated sheet S by radiant heat. A method is used in which the decorative sheet S in a softened state is brought into close contact with the cavity surface CS of the female mold by softening and then applying vacuum suction by a vacuum device through an air passage 505 formed in the female mold 501. ing.

[0005]

However, the above-described method using the conventional apparatus and the mold structure has the following problems. That is, after the decorative sheet S is heated, the cavity surface C of the female mold 501 is formed by vacuum forming.
It is shaped so as to adhere to S.
At the bottom and corner portions of the cavity surface CS, the amount of stretching of the decorative sheet S becomes larger than at other portions, and a phenomenon occurs that the portion becomes thinner at that portion. Therefore, for example, in the case of using a printed transfer sheet, there is a problem that the pattern does not become a desired shape due to uneven stretching of the sheet, or the color becomes lighter in a portion where the stretching is excessive. However, there is also a problem that the sheet is torn or wrinkled.

In the case of using a functional film such as a film to which a weather-resistant formulation has been applied, if the film becomes thinner than intended, the functions such as the weather resistance will be reduced accordingly. In order to secure the minimum thickness required for the film, the thickness of the material film before stretching must be increased, which leads to a problem that the cost increases.

The present invention has been made in order to solve such a problem, and it is possible to reduce the partial thinning of the decorative sheet after shaping, and to reduce the function of the sheet and to improve the sheet. It is an object of the present invention to provide a decorative molding die capable of preventing extreme deformation and lightening of a printed pattern or the like, or occurrence of tearing or wrinkling of a sheet.

[0008]

The structure for achieving the above object will be described with reference to FIG. 1 showing an embodiment. The decorative molding die of the present invention comprises a female mold 1 and a male mold. A cavity is formed between the molds composed of the mold 2, and the decorative sheet S is supplied between the molds 1 and 2 and the sheet S is heated by the heating means 5 in a state where the sheet S is clamped to the female mold 1. After being softened, the decorative sheet S is brought into close contact with the cavity surface CS of the female mold 1 by vacuum suction through the air passage 11 formed in the female mold 1, and then the mold is clamped to supply the molten resin into the cavity. By doing so, in the mold used in the process of molding the decorative molded product, the clamping surface 12a of the decorative sheet in the female mold 1 is positioned outside the cavity edge CE of the female mold 1 by a predetermined dimension A. And the male mold 2 side by dimension B from the mold opening surface P With protruding, dimensions A: B
Is in the range of 1: 1 to 50: 1.

Here, in the present invention, it is preferable that the projecting dimension B of the sheet clamping surface 12a from the mold opening surface P is 1 mm or more. Further, the protrusion may be inclined toward the cavity, but the ratio of the minimum value of the dimension B to the dimension A must be within the above range. Further, the ratio of the dimension A from the cavity edge CE to the sheet clamp surface 12 to the above-mentioned protrusion amount B is 1: 1 to 5 as described above.
0: 1, more preferably A: B is 1:
It is in the range of 1-5: 1.

The clamp jig for clamping the decorative sheet S to the sheet clamp surface 12a of the female die 1 is heat-resistant, and has a heat resistance and a sheet clamp surface 12a of the female S and the female die 1. The material is not particularly limited as long as it can provide a hermetic seal with the material, but it is preferable to use a material having a low thermal conductivity.

In the decorative molding step using the mold of the present invention, the decorative sheet S is heated and softened while being clamped with respect to the female mold 1, and then the cavity of the female mold 1 is evacuated by vacuum suction. Fig. 2
As illustrated in the above, a method of pre-stretching by pressing the decorative sheet S in a softened state to the vicinity of the cavity surface of the female die 1 by the pressing core 6 can also be adopted.

According to the decorative molding die of the present invention, the decorative sheet S is located outside the cavity edge CE of the female mold 1 by the dimension A, and the male mold is located closer to the mold opening plane P than the mold opening surface P. Since the clamped heating sheet S is clamped to the surface 12a protruding by the dimension B to the second side, when the clamped heating sheet S is heated by a heating plate or the like, the area that is actually softened without being affected by cooling by the female mold 1 increases. At the same time, the effect of friction between the sheet S and the female mold 1 during stretching can be reduced.

That is, according to the conventional mold shown in FIG. 5, only the region indicated by b in FIG. 5 is substantially softened by the effect of cooling due to contact with the female mold 501, whereas the conventional mold shown in FIG. According to the mold, the region indicated by a in FIG. 1 is in a softened state,
In the subsequent vacuum forming step or the pre-drawing step using a pressing core, the area to be actually drawn becomes wider, so that the sheet thickness after shaping by vacuum forming can be reduced, and at the same time, the clamp surface 12a and the cavity edge CE are formed. , The influence of friction due to contact with the female mold 1 does not affect the sheet S covering the surface of the product.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partial sectional side view showing a main part of an embodiment of the present invention, in which a decorative sheet S is clamped to a female mold 1 in a mold open state. ing.

Of the female mold 1 and the male mold 2 opposed to each other, the female mold 1 is attached to the moving die plate side of the injection molding machine, the male mold 2 is attached to the fixed die plate side, and the female mold 1 side is attached. The mold is clamped by moving to the male mold 2 side. In addition, the female mold 1 has an air passage 11 communicating with a vacuum device for vacuum forming the decorative sheet S, and the male mold 2 has a mold 1 in a clamped state.
A resin flow path 21 for injecting the molten resin into the cavity formed by 2 is formed.

Above the female mold 1, a sheet roll 31 around which the decorative sheet s is wound and a sheet feeder 32 for feeding the decorative sheet S downward from the sheet roll 31 by a constant pitch. The sheet supply mechanism 3 is provided. The sheet supply mechanism 3 supplies a required amount of the decorative sheet S to the female mold 1 every time the injection molding is completed and the mold is opened in the mold clamped state.

The female mold 1 is provided with a frame 42 which is moved back and forth in the mold clamping / mold opening direction by an ejector device 41, and thereby the decorative sheet S is moved around the female mold 1 in a peripheral portion thereof. The decorative sheet S has a sheet clamping surface 4 which is a surface of the frame 12 fixed to the frame 42 and the mold opening surface P of the female die 1. 12a to be clamped.

That is, the decorative sheet S is supplied by the sheet supply mechanism 3 in a state where the frame body 42 has advanced toward the male mold 2 from the state of FIG. 1 and then, as shown in FIG.
Is retracted, and the four sides are sandwiched between the frame body 42 and the sheet clamp surface 12a. The frame-shaped body 12 fixed to the mold opening surface P of the female mold 1 is located outside the cavity edge CE of the female mold 1 by a dimension A outside the cavity edge CE.
And the ratio A: B of the dimension A thereof to the height of the frame body 12, that is, the dimension B formed by the sheet clamping surface 12a and the mold opening surface P of the female die 1 is: , 1: 1-5
The range is 0: 1.

In the clamped state of the decorative sheet S as described above, the heating plate 5 is inserted between the female die 1 and the male die 2, and the decorative sheet S is heated and softened by the radiant heat. Thereafter, the decorative sheet S is shaped so as to be in close contact with the cavity surface CS of the female mold 1 by vacuum suction through the air passage 11. Thereafter, after the female mold 1 and the male mold 2 are clamped, a molten resin is injected into the cavity formed between them through the resin flow path 21 so that a part of the surface of the decorative sheet is provided. A decorative molded product covered with S is obtained.

Before the decorative sheet S is vacuum-formed, as shown in FIG. 2, the pressing core 6 is pre-stretched by pressing the pressing core 6 against the softened decorative sheet S as shown in FIG. Is also good.

The sheet clamp surface 12a of the female mold 1
In the above embodiment, the frame 12 is fixed to the mold opening surface P of the female mold 1 so that the surface protrudes by the dimension B from the mold opening surface P. For example, as shown in a cross-sectional view of a female mold according to another embodiment of the present invention in FIG. 3, the mold opening surface P is located at a position outside the cavity edge CE of the female mold 1 by a dimension A. The sheet clamping surface 12a may be formed by raising the dimension B to form the step 12 ', and the shape of the step 12' is shown in FIG. 4 according to still another embodiment of the present invention. An inclined surface may be used as shown in the sectional view of the female mold.

Next, an example of actually manufacturing a decorative molded product using the above embodiment will be described together with a comparative example. (Example 1) The decorative sheet S (material: polymethyl methacrylate (PMMA), thickness: 16 mm, dimension B: 8 mm (A: B = 2: 1) in the mold structure of FIG. 0.125 mm) was clamped to soften by heating, then preliminarily stretched using the pressing core 6 shown in FIG. 2, brought into close contact with the cavity surface CS by vacuum suction, clamped, and injected molten resin. The appearance of the obtained decorative molded article was examined, and it was confirmed that the decorative article had a good appearance without defects such as wrinkles.

Example 2 The same decorative sheet S as described above was clamped by setting the dimension A to 48 mm and the dimension B to 1.2 mm (A: B = 40: 1) in the mold structure of FIG. It was softened by heating, brought into close contact with the cavity surface CS by vacuum suction, and then clamped to inject molten resin. The appearance of the obtained decorative molded article was examined, and it was confirmed that the decorative article had a good appearance without defects such as wrinkles.

Comparative Example 1 Decorative molding was performed in the same manner as in Example 1 except that the decorative sheet S was clamped on the mold opening surface P connected to the cavity of the female mold 501 by the mold structure shown in FIG. The product was molded, but the decorative sheet S had wrinkles at the corners of the molded product.

Comparative Example 2 Using the mold structure shown in FIG. 1, a dimension A was 16 mm and a dimension B was 20 mm (A: B =
0.8: 1), the decorative molded product was molded in the same manner as in Example 1 except for the above, but the decorative sheet S had wrinkles at the corners of the molded product.

Comparative Example 3 Using the mold structure shown in FIG. 1, a dimension A was 48 mm and a dimension B was 0.8 mm (A: B =
Otherwise, the decorative molded product was molded in the same manner as in Example 1 except that the decorative sheet S had wrinkles at the corners of the molded product.

However, the dimensions of the dies used in the examples and comparative examples are as follows. Female type in FIG. 1: Vertical when viewed from male type (corresponding to vertical in FIG. 1)
The cavity is 400 mm long and 350 mm wide (corresponding to the depth in FIG. 1), and the cavity is 180 mm long, 180 mm wide and 80 mm deep.

The male mold shown in FIG. 1 has a length of 150 mm, a width of 150 mm and a height of 65 mm.
mm. The dimensions of the mold in FIG. 5 were the same as above.

[0029]

As described above, according to the present invention, the decorative sheet is mounted on the sheet clamp surface which projects a predetermined amount B from the mold opening surface outside the cavity edge of the female mold by a predetermined dimension A. Clamp against the mold and its A:
Since B is in the range of 1: 1 to 50: 1, the region which is substantially softened by heating becomes wider than before, and at the same time, friction due to friction with the female mold during stretching of the sheet during vacuum forming or pre-stretching. As a result, the effect of reducing the thickness of the sheet after shaping can be reduced,
Without deteriorating the function of the sheet, it is possible to reduce extreme deformation and lightening of the printed pattern, or to reduce the occurrence of tears and wrinkles in the sheet.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional side view showing a main configuration of an embodiment of the present invention, showing a state in which a decorative sheet S is clamped to a female mold 1 in a mold open state.

FIG. 2 is an explanatory diagram of a pre-stretching step using a pressing core used as needed in an embodiment of the present invention.

FIG. 3 is a sectional view showing a female mold structure according to another embodiment of the present invention.

FIG. 4 is a sectional view showing a female mold structure according to still another embodiment of the present invention.

FIG. 5 is an explanatory view of a conventional apparatus using an in-mold molding method for insert-molding a decorative sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Female mold 11 Air passage 12 Frame-shaped body 12a Sheet clamp surface 2 Male mold 21 Resin flow path 3 Sheet feeding mechanism 4 Clamp mechanism 41 Ejector device 42 Frame 5 Heating plate 6 Pressing core S Decorating sheet CE Cavity edge P Mold opening surface

Claims (1)

[Claims] 1. A cavity is formed between a female mold and a male mold, and a decorative sheet is supplied between the molds and clamped against the female mold. After heating and softening, the decorative sheet is brought into close contact with the cavity surface of the female mold by vacuum suction through an air passage formed in the female mold, and then the mold is closed and molten resin is supplied into the cavity. A mold used in a step of molding a decorative molded product, wherein the clamping surface of the decorative sheet in the female mold is located outside the cavity edge of the female mold by a predetermined distance A, and It protrudes from the mold opening surface toward the male mold by a distance B, and the distance A: B is 1: 1 to 50: 1.
A decorative molding die, characterized by being in the range described above.