JPH05262345A - Plastic case - Google Patents

Abstract

PURPOSE:To obtain a plastic case, whose adhesive strength and fine appearance are improved, by bending a plastic sheet and applying an adhesive to a mating face to be laminated with the other face. CONSTITUTION:A plastic sheet 1 is bent, and an adhesive 3 is applied to a mating face 2 to be laminated with the other face to make a plastic case. In this case, in the vicinity of an end portion 21 of the mating face 2, the adhesive 3 is applied wider, or the amount of the adhesive to be applied per unit area is increased, more than other portions where the adhesive is applied. According to this method, the plastic case excellent in its adhesive strength at the end portion of the mating face and also excellent in its fine appearance can be obtained in spite of the less amount of the adhesive to be applied as a whole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic case obtained by bending a plastic sheet and applying an adhesive to the mating surfaces of the plastic sheet and then laminating the plastic sheet.

[0002]

2. Description of the Related Art Conventionally, in the manufacture of a plastic case, a plastic sheet provided with folding ruled lines is bent, and an adhesive is applied to a mating surface to perform a laminating process. Apply adhesive to the side of the upper case that corresponds to the side, bend it into a cylinder, and attach it.

At both ends of the side surface of the case, there are usually formed folding flaps which serve as lids for closing both ends of the cylindrical case when the product is stored. The folded plastic case is delivered to the user in a flat folded state, opened in a tubular shape by the user's box making machine, assembled into a box, put the contents, and then bend the folding flap to make a lid. Ship.

[0004]

The above-mentioned conventional plastic case is assembled into a box by the user's box making machine, and when the folding flap is folded, the folding flap is bent at 90 degrees at a high speed. Is stressed and peels off if the adhesion is insufficient. On the other hand, there is a problem in that the amount of adhesive used must be reduced as much as possible from the viewpoint of environment and work.

[0005]

According to the present invention, in a plastic case in which a plastic sheet is folded and adhesive is applied to the mating surfaces, the amount of adhesive or the application width of the adhesive near the ends of the mating surfaces is adjusted. It is a plastic case characterized in that it is made larger than other applied parts.

The present invention will be described below with reference to the drawings. 1 is a perspective view showing an example of the plastic case of the present invention, FIG. 2 is a development view of the plastic case of FIG. 1, and FIG.
[Fig. 3] is a plan view illustrating a method for measuring the peel strength of an end of a mating surface.

In the present invention, the plastic sheet 1 is bent,
In a plastic case in which the adhesive 3 is applied to the mating surface 2 and bonded together, the plastic is characterized in that the application width near the end 21 of the mating surface 2 or the amount of the adhesive 3 applied is larger than that of other applied parts. It is a case.

In the present invention, as the plastic sheet, a polyvinyl chloride sheet, a polyethylene terephthalate sheet and the like are suitable. Further, the ruled line 4 may be formed in advance along the line to be bent, or may be bent in a cylindrical shape. In short, the ruled line 4 may be formed in a cylindrical shape and the opposite ends may be overlapped to form the mating surface 2.

As the adhesive 3 to be used, an appropriate one such as a normal hot melt adhesive or a solvent adhesive can be used.

As a method of applying the adhesive 3 in the present invention, when an adhesive discharge device such as a hot melt adhesive is used, a mating surface end 21 of the photoelectric tube is formed by combining a photoelectric tube and a solenoid valve. Is detected and the opening / closing degree of the adhesive discharge device is adjusted by the solenoid valve to adjust the discharge amount.

When the adhesive is transferred and applied to the mating surfaces by using a coating roll like a solvent-based adhesive,
You may use the application roll which dug the application pattern which made the application width of the adhesive agent near the edge part of a mating surface larger than other application parts.

In the present invention, as the coating shape of the adhesive 3, the coating width of the end portion 21 of the mating surface or the coating amount per unit area is 120% to 400% of the coating width of another portion or the coating amount per unit area. %, The sufficient peel strength of the mating face end portion 21 can be maintained even if the coating width or coating amount in the central portion is reduced to 50 to 80% of the conventional value.

If the coating width or the coating amount per unit area at both ends is less than 120% of the coating width or the coating amount per unit area of the other portion, the coating width or the coating amount per unit area of the other portion will be It exceeds 80% of the conventional level, and it is not possible to achieve the intended purpose of reducing the total coating amount and maintaining the adhesive strength at a conventional level. 400% again
On the contrary, the coating width of the other portion or the coating amount per unit area becomes less than 50% of the conventional value, so that the adhesive strength is uncertain, the quality is excessive, and the aesthetic appearance is deteriorated.

[0014]

EXAMPLE As an example, a hard polyvinyl chloride sheet having a thickness of 0.3 mm was used to form a cubic case having sides of 50 mm as shown in FIG.
A mating surface 2 is provided to spread out and punch out, and a hot-melt type adhesive as the adhesive 3 has a width of 6 mm over the length of 6 mm at both ends 21 and the length of the other applied portion in the central portion. It was applied so that the width would be 1.5 mm over 36 mm. Total length is 48mm, total coating amount is 0.1g
Became.

As a comparative example, the thickness is 0.3 m as in the embodiment.
A hard polyvinyl chloride sheet of m was punched out in the same manner as in the example, and the same adhesive 3 as in the example was applied with a width of 3 mm over the entire length of the mating surface 2 of 48 mm. Total application amount is 0.14g
Became.

In the above-mentioned examples and comparative examples, adhesives were applied and bonded together, and then flattened into a state before being applied to a box making machine. Next, as shown in FIG.
Hook 5 made by bending a metal rod of mm
Insert 5 mm, attach one of the hooks to the spring scale, pull the spring scale at a speed of 20 cm per minute, and attach the end 2 of the mating surface.
The load until 1 peeled was measured.

As a result, the example of the present invention was 4.6 kg. On the other hand, the weight of the comparative example was 3.7 kg. Therefore,
The total amount of application was 0.1 g in Example and 0.14 g in Comparative Example, and although the application amount of the adhesive 3 was reduced in the present invention as a whole as compared with the conventional product, the mating surface end portion 21 It can be seen that the adhesive strength is excellent. It should be noted that the larger the length of the mating surface, the larger the proportion of the other coating portions, and therefore the coating amount can be saved.

[0018]

INDUSTRIAL APPLICABILITY According to the present invention, in a plastic case in which a plastic sheet is folded and adhesive is applied to the mating surfaces, the adhesive width near the end of the mating surface or the application amount per unit area can be changed. Since it is a plastic case characterized by making it larger than the applied part, compared to the conventional product, despite the fact that the application amount of adhesive was reduced as a whole, the adhesive strength of the mating surface end is excellent,
It is an excellent product that has a beautiful appearance.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a plastic case of the present invention.

FIG. 2 is a development view of the plastic case of FIG.

FIG. 3 is a plan view illustrating a method of measuring peeling strength at an end of a mating surface.

[Explanation of symbols]

 1 plastic sheet 2 mating surface 21 edge 3 adhesive

Claims (1)

[Claims] 1. In a plastic case in which a plastic sheet is folded and adhesive is applied to the mating surface, the adhesive is applied in the vicinity of an end of the mating surface, or the application amount of the adhesive per unit area is adjusted to the other applied portion. A plastic case characterized by being made larger.