JPH0221365Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is applicable to single units of a certain volume such as tape cassettes for video tape recorders, floppy discs, video discs, digital audio discs, and sheets of photosensitive material. This invention relates to a synthetic resin container suitable for storing products such as film, photographic paper, and IC printed boards.

[Prior art]

Such synthetic resin containers with small volumes can be molded into three-dimensional shapes by direct injection molding, but in the case of cases that store items over a certain volume, such as tape cassettes for video tape recorders, Since it is impossible to perform three-dimensional molding by direct injection molding, a method is used in which a box is manufactured from a spread plate (blank sheet). (Jitsukai 58-
916, Utility Model Application Publication No. 58-917).

Conventionally, the development plate of such synthetic resin containers has been made by cutting a synthetic resin flat plate of a certain thickness extruded into a long length from a T-die to make a plate of a certain size, and then cutting the plate at the crease (hereinafter referred to as "K-line"). )
They were produced by compression shaping or cutting, punching out the notches, and in some cases embossing the surface. This conventional manufacturing method requires a large number of man-hours and is inefficient, has a high rate of defective products, and has disadvantages in terms of cost and industrial waste generation because cutting allowances and notch allowances are discarded. Ta.

In order to eliminate the drawbacks of the prior art as described above, the inventor of the present invention first proposed the production of a developing plate for such a synthetic resin container by injection molding (Japanese Patent Laid-Open No. 152830/1983). Public bulletin). In other words, it has been considered difficult to injection mold a deployable plate with a wide area beyond a certain level using resin, and no attempt has been made to do so. It has been found that by doing so, the drawbacks of the prior art as described above can be completely eliminated.

However, the display part or the design part of the tape cassette for the video tape recorder inside the case can be seen from the outside while it is packed in the case.
It is impossible to make parts transparent or translucent, and the process is very expensive because one part of the case is punched out and a separate transparent or translucent sheet is attached to that part.

In addition, there are synthetic resin containers that have transparent windows formed by printing on a transparent flat plate, and are processed by wire processing and punching, but they have a high incidence of defective products and are very expensive. It was easy to get scratches.

[Purpose of invention]

The present invention eliminates the drawbacks of conventional manufacturing methods as described above, and eliminates the need for cutting, punching, embossing, and pasting of transparent sheets, reducing materials and man-hours, making it more efficient and disadvantageous in terms of cost and environmental protection. The purpose of the present invention is to provide a synthetic resin container with a window portion without a window.

[Structure of the idea]

The above object of the present invention is to provide a container made of polypropylene resin, which is made by injection molding a developing plate having a diagonal line part and a cutout part, and then forming the same into a box, which has a melt index of 15 to 50 g as the resin material. /Ten
This is achieved by using a polypropylene resin container with a window, which is made of polypropylene resin and has a window that is at least 0.05 mm thinner than the thickness of the front or back part and has improved transparency by at least 10%.

Hereinafter, the content of the present invention will be explained in more detail with reference to the accompanying drawings.

In the present invention, a polypropylene resin container 1 with a window in the shape of a rectangular parallelepiped and having an open opening on one side as shown in FIG. It is manufactured by box-making.

In FIGS. 2 and 3, the unfolding plate 2 or the unfolding plate 2' is a front part 4 or 4'; a back part 5 or 5'; a left side part 6 or 6'; a right side part 7 or 7'; a bottom part 8. or 8'; left side overlapping part 9 or 9'; right side overlapping part 10 or 10'; flaps 11, 11
a or 11', 11'a, Kei line part 12 or 12'
and a window portion 20 or 20', 21, 22,
By forming these into a box, a polypropylene resin container 1 as shown in FIG. 1 is formed. In Fig. 1, the correspondence of each part of the unfolding plate in Fig. 2 is written except for the flaps 11, 11a and the highlighted line part 12, and the correspondence of each part of the unfolding plate in Fig. 3 is also in accordance with this. .

Conventionally, a synthetic resin container 1 as shown in FIG.
In the case of a case that stores items over a certain volume, a synthetic resin flat plate of a certain thickness that has been extruded into a long length from a T-die is cut and a perspective view shown in Fig. 2 or 3 is applied. After making the cutout and window into a rectangular plate without notches or punching,
2 or 12' by pressing or cutting,
Next, hatched notches 13, 14, 15, 1
6 or 13', 14', 15', 16' and window part 20
Or 20', 21, 22 are punched out and a transparent or semi-transparent sheet is pasted on the window part 20 or 20', 21, 22. Depending on the case, the front part 4 or 4' is embossed to form a development board. was created and made into boxes.

According to the present invention, the developing plate 2 or 2' as shown in FIG.
Alternatively, the containers 20', 21, 22, and in some cases, may be made by injection molding so as to have irregularities on the front surface, etc., and then made into a box to produce a polypropylene resin container 1 as shown in FIG.

The developed plate formed by the above method has an average thickness of 0.3
~3mm and has an area of ^100cm2 or more, so if the molten resin is not uniformly and quickly filled from the gate into the molding cavity during injection filling of synthetic resin, the distribution of the resin will become uneven and the density will increase. There may be areas where the resin does not reach properly, and deformation may occur after molding.Especially when printing on a developing plate and heating it to quickly dry it, the deformation becomes severe, causing kinks and warping. This will cause damage to the appearance.

Therefore, in the present invention, the synthetic resin to be injection molded (including in-mold vacuum injection molding method and known injection molding method using multistage mold) preferably has an MI (melt index) of 5 to 80 g/10 min. 15-50
g/10 minutes, and various thermoplastic resins can be used as long as the haze degree of the window is 50% or less, but polyolefin thermoplastic resins, polystyrene thermoplastic resins, and ABS thermoplastic resins are particularly expensive, Suitable for manufacturing accuracy and dimensional stability. In particular, the melt index (ASTM D-1238) is 15 to 50g/
10-minute polypropylene resin is suitable in terms of rigidity, transparency, scratch resistance, and wire strength. These thermoplastic resins contain various self-color pigments (titanium oxide, talc, mica, calcium carbonate, clay, etc.)
and various types of carbon black, various colored pigments, various metal powders (aluminum powder, tin powder, aluminum paste, etc.), various metal fibers,
Various organic or inorganic fiber substances such as glass fiber and carbon fiber, various other coloring dyes, various antistatic agents, various silicones, various surfactants, lubricants such as sodium stearate, various foaming agents, etc. Various known additives such as various antioxidants can be added. Furthermore, when injection molding is performed in the method of the present invention, the injection port (gate port) for the molten thermoplastic resin is not limited to one location, but can be provided at a plurality of locations. By doing so, the flow of the thermoplastic resin improves during injection molding, and it is possible to prevent the occurrence of a boundary line where the flow of the thermoplastic resin joins, which is called a weld line. These injection ports (gate ports) should be placed at the notch 1 so that they do not remain on the surface of the container.
3, 14, 15, 16 or flap portions 11, 11
It is preferable to provide it in the portions G ₁ to G ₁₂ of the overlapping portions 9 and 10 of the side surfaces 9 and 10. In particular, G ₁ , G ₃ , G ₄ in Figure 2,
It is preferable to provide a resin injection port (gate port) at at least one of G ₇ , G ₁₀ , and G ₁₁ . Of course, it is also preferable to use a combination with a gate opening provided at one or more locations near the center of gravity on the inside of the expansion plate (on the inner surface side in contact with the product), preferably near symmetrical positions laterally or vertically.

There are various known shapes for the resin injection inlet (gate), which will be described later, but in order to avoid leaving gate marks on the surface of the container, pin gates are preferable when forming on a flat surface. Side gate is preferable if you want to make a profit in (part).

In any case, in this invention, the number and position of the resin injection ports (gates) change depending on the shape of the developing plate, the fluidity (melt index) of the thermoplastic resin, etc., so the invention is not limited to the description of the invention. It is preferable that it be located inside the container (inner surface side that contacts the product) or in a place where it is not visible on the cross section or surface when the container is packaged. Other desirable positions for the resin injection port (gate) include the notches 13, 14, 15, and 16 of the expansion plate in Fig. 2 when using a side gate or the like.
Preferably, the product ends G ₁ , G ₇ , G ₃ , G ₁₀ are used, and other desirable positions for using pin gates or other gates include positions where the resin injection port does not appear on the surface after forming the box, for example: G ₅ , G ₆ , G ₈ , G ₉ of the overlapping parts 9 and 10 on the left and right sides of the development plate in Fig. 2,
Or G ₃ , G ₄ of the symbol of flap 11, 11a,
It is preferable that the thermoplastic resin be provided at one or more locations on the front, back, and end portions of G ₁₀ and G ₁₁ , preferably on the left and right, or in the vicinity of vertically symmetrical positions where the thermoplastic resin can flow in approximately the same amount of time to the four corners.

Particularly preferably, when the injection port (gate) for the thermoplastic resin is to be provided at only one location, it is provided at the position G ₃ or G ₁₀ or G ₁ or G ₇ in FIG. If two locations are provided, they should be located at G ₃ and G ₁₀ or G ₁ and G ₇ in Figure 2.

In any case, in this invention, the number of resin injection ports (gates) is determined depending on the shape of the developing plate, the fluidity of the thermoplastic resin (melt index), the ease of generating gate marks, the ease of generating weld lines, etc. Since the position and shape change, the present invention is not limited to the above description, and any number or shape can be adopted at any position on the expansion plate. ) is desirable from the viewpoint of appearance and fluidity of the resin.

According to the present invention, when manufacturing a synthetic resin container 1 as shown in FIG. 1, a developing plate 2 or 2' as shown in FIGS. 2 and 3 is used, and the cross-sectional shape is as shown in FIG. 4 or 5. Preferably, the shape is as shown. The plate thickness t is generally from about 0.5 mm to several mm, and by making the wire part 5% or more thinner than the plate thickness t,
Easy to manufacture boxes.

The thickness of the window should be at least 0.05mm thinner than the expansion plate.
The transparency of the window can be emphasized by applying a molding (texturing) process to the surface other than the window.

Letting the haze degree of the window portion be H and the haze degree of the other portions be H', it is desirable that H≦50% and H'/H≧1.3.

To reduce the haze level of the window, it is best to reduce the thickness or select a resin grade with a low haze level. To increase the degree of haze in other parts, it is better to increase the thickness, or to lower the transparency by applying a molding process to the surface as described above. Alternatively, printing, painting, etc. may be applied. The molding process applied to the surface may be done on one side or both sides.

Before manufacturing the box, the outer or inner surfaces of the front part 4 or 4' and the back part 5 or 5' are embossed, grooved, lettered and recessed, and marked and painted to improve the appearance and ease of handling. Improvements are also made selectively. Furthermore, by applying a fine patterning process to a portion of the surface, it is possible to provide writing properties with a pencil, ballpoint pen, magic marker, etc. In conventional manufacturing methods, these were performed by embossing, but with the present invention, these surface treatments can also be performed during injection molding.

Adding 0.2 to 5% by weight of silicone compounds such as dimethylsiloxane to thermoplastic resin improves fluidity, moldability, and mold release properties during molding, as well as sink marks, warpage, and post-molding slippage and abrasion resistance. can do. Additionally, by adding an antistatic agent to the thermoplastic resin, it is possible to make it difficult for dirt and dust to adhere to the container, or by adding a foaming agent to the thermoplastic resin, the appearance of the container can be changed to improve its feel and make it lighter. It may also be optionally possible to do so.

〔Example〕

Next, in order to further clarify the effects of the present invention, examples are listed below.

(1) A mold for injection molding of a developing plate as shown in Fig. 2 was prepared. So that the dimensions of the expansion plate are as follows:
Designed the mold. The inlet is G ₃ in Figure 2.
It was set as one location.

Vertical and horizontal dimensions of the unfolding plate: The longest part is 247mm x 237mm Thickness of the unfolding plate: 0.8mm Embossed on both the front and back sides except for the window Haze level: 60% Dimensions of the transparent part (window): Height 70mm x 90mm Thickness 0.6mm smooth surface, Haze degree: 20% Dimensions of the diamond part: Width 1.5mm, depth 0.25mm Cross-sectional shape of the diamond part: As shown in Figure 4 Dimensions of notches 13 and 14 Length approximately 70mm, width 20 mm Dimensions of notches 15 and 16: Polygon with the longest part being 37 mm x 28 mm (2) Using this mold, molten thermoplastic resin with the following composition was injection molded: Polypropylene resin manufactured by Mitsui Petrochemicals Co., Ltd. Grade No. J-950D (MI-40g/10 minutes)
...96.8% by weight Dimethylpolysiloxane, KF-96 (product name) manufactured by Shin-Etsu Silicone Co., Ltd. ...0.1% by weight Titanium oxide ...2% by weight Antistatic agent Electrostripper manufactured by Kao Soap Co., Ltd. ...0.1 Weight% (3) Print characters in two colors, black and red, on the injection molded development plate 2 using a silk screen printing method and heat at 50℃.
After drying with hot air and fixing the printing ink to the development plate, pressurize with a hot plate at 80℃ and stamp the product name with aluminum foil.Then, assemble this and weld the overlapping parts with an ultrasonic bonding machine to obtain the approximate dimensions. is 192mm×105
A case for a videotape cassette measuring 28 mm x 28 mm was manufactured.

When the number of boxes manufactured is 300,000, the manufacturing cost is reduced to 40% compared to the conventional manufacturing method that includes cutting and punching processes, and the incidence of defective products is 11% compared to the conventional method. In this invention, it was 1%.

[Effect of idea]

According to the present invention, as the man-hours are reduced as mentioned above, manufacturing costs are lowered, warping and twisting of the development plate is greatly reduced, flatness is improved, the process is stabilized, and there are no gate marks on the surface. As a result, the quality of appearance, precision, finished surface, etc. has improved, work automation has been achieved, there is no wire cracking, no cutting waste, dropouts have been greatly reduced, and industrial waste has been reduced. be able to.

The present invention is not limited to the embodiments, but can be applied to a wide range of applications, for example as shown below.

(1) The shape of the expansion plate is not bilaterally symmetrical; for example, the shape of the front part and the shape of the back part may be different.

(2) Even if the thickness of the side part is the same as the remaining thickness of the wire part, the strength can be maintained by overlapping joints.

(3) The shape of the notch can be various shapes such as rectangle, square, trapezoid, semicircle, semiellipse, equilateral triangle, isosceles triangle, and arrow shape.

(4) The remaining thickness of the wire part may be partially thickened to improve the flow of resin during injection molding.

(5) The surface of the mold is processed to have a transparent window in one or more places on the development plate, and the inside and outside surfaces of the case are marked with the product name, company name, picture, etc. It can have shapes (texturing) such as stripes, horizontal stripes, lattice patterns, fine-grain surface textures, etc. Tokyo Bearon is a concrete grained sample.
There are over 210 types of "Bearonshibo" published by Co., Ltd.

(6) For injection molding, the thermoplastic resin can be a copolymer or a mixed resin of two or more thermoplastic resins.

(7) Thermoplastic resins contain 1 color pigment or color dye.
A species or multiple species can be added.

(8) After the development plate is injection molded, printing and labeling processes are selectively added before and after the box manufacturing process.
Marks and characters can be attached.

[Brief explanation of the drawing]

Fig. 1 is an external view of a polypropylene resin container according to the present invention, Figs. 2 and 3 are plan views of an embodiment of the expansion plate, and Figs. 4 to 9 are A in Fig. 2.
FIG. 3 is a sectional view of the developed plate taken along plane -B or plane A'-B' in FIG. 3; FIGS. 7 to 9 are representative examples of changes in the shape of the corner portions. 1... Polypropylene resin container, 2, 2'...
...Development plate, 12,12'...K line part, 13,1
4, 15, 16, 13', 14', 15', 16'...
...Notch, 20, 20'21, 22... Window, G ₁
~G ₁₂ ...Resin injection port (gate).

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A container made of polypropylene resin, which is made by injection molding a developing plate having one or more of a wired part and a cutout part, and then made into a box, which is made of polypropylene resin, and A polypropylene resin with a window, characterized in that it uses a polypropylene resin with a melt index of 15 to 50 g/10 minutes, and has a window that is 0.05 mm or more thinner than the thickness of the front or back part and has improved transparency by 10% or more. Container made. (2) Claim 1 for registration of a utility model, characterized in that both the front and back sides of the expansion plate other than the window are patterned, and the window is textured on one or both of the front and back sides. A polypropylene resin container with a window as described. (3) The polypropylene resin container with a window portion according to claim 1 or 2 of the utility model registration claim, wherein the haze degree of the window portion is 50% or less.