JPH1080268A - Petri dish having protrusions on inner circumference wall and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a petri dish resistant to the separation of a medium and to provide an effective method for one-piece molding of the petri dish. SOLUTION: This petri dish has inclined protrusions 3 directing obliquely upper side from the inner bottom. The petri dish is produced by one-piece injection molding of a synthetic resin using a die body 2 and an inner mold 3 having inclined grooves 31 on an outer periphery, or by one-piece injection molding of a synthetic resin using a die body 2 and a divided inner mold consisting of a pair of side inner molds having a groove on the outer periphery and a center inner mold to be placed between the side inner molds and having no groove on the outer periphery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a petri dish, particularly a petri dish having a projection on an inner peripheral wall suitable as a test container for culturing bacteria by filling and using a solid medium and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, when a culture test of bacteria is carried out using a solid medium consisting of agar jelly containing a growth supporting component and the like, a petri dish is generally used because of its simplicity.

However, since the inside of the petri dish has a smooth surface, for example, when it is necessary to transport the petri dish filled with the culture medium to a specialized inspection organization after collecting bacteria, vibration during the transportation is required. In many cases, the medium is peeled off from the Petri dish due to dropping or dropping. As a result, there has been a problem that the colony formation of bacteria is hindered and the determination becomes impossible.

[0004]

The inventors of the present invention have conducted various studies with the aim of preventing the detachment of the culture medium. As a result, if a protrusion is formed on the inner peripheral wall of the petri dish, it is more effective for locking with the culture medium. If there is, and when using the normal type,
As shown in FIG. 5, the injection molding cannot be performed because the inner die cannot be removed due to the presence of the projection. However, if the inner die or the divided inner die that forms the inclined projection is used, the die is removed by rotation or sequentially moved. The present invention has been completed, and it has been found that an integrated molded article of a petri dish having a projection on the inner peripheral wall having the above-mentioned separation preventing function can be manufactured extremely efficiently.

[0005]

That is, a first aspect of the present invention is a petri dish characterized in that a projection is formed on an inner peripheral wall, and a second aspect of the present invention is an outer mold and a slant groove on an outer peripheral portion. A method of manufacturing a Petri dish having an inclined projection on the inner peripheral wall, characterized by performing injection integral molding with a synthetic resin using an inner mold having an outer mold, and a third aspect of the present invention is an outer mold and a circle on the outer peripheral portion. Using a split inner die composed of two side inner die portions having a groove, a vertical groove or a lateral groove and one center inner die portion having no groove in the outer peripheral portion used between the side inner die portions. A method for producing a petri dish having a hemispherical, vertical or horizontal projection on an inner peripheral wall, wherein injection molding is performed using a synthetic resin.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the protrusions on the inner peripheral wall of the petri dish may be of any specific shape such as hemispherical protrusions, vertical protrusions, and horizontal protrusions. The use of inclined projections is advantageous because injection molding can be performed without using an inner mold as a divided body, as described later, and a sufficient medium fixing action can be obtained. In this case, the output width of the inclined projection is 0.5 to 5.0 mm, the length is 10 to 20% of the inner circumference of the petri dish, and the inclination angle is 10 to 30 ° of elevation. Particularly good results are obtained in terms of properties and medium fixation. The number of projections is usually preferably 2 to 4 in terms of practicality.

[0007] The projection on the inner peripheral wall of the petri dish can be formed by fixing the projection formed as a separate member to the inner wall of the petri dish with an adhesive or the like, but it is natural that an integrally molded body is desirable.

In the case where the inclined projections are integrally molded, an inner mold having an inclined groove on the outer periphery as described above is used, and after the synthetic resin is injected, the inner mold is appropriately rotated.
The inner die rises by the screwing movement of the inclined protrusion and the inclined groove, and can be removed from the outer die.

In the case where hemispherical, vertical or horizontal projections are integrally molded instead of inclined projections, an inner mold having a three-piece structure as described above is used. And then move the inner mold part on one side to the center to release the engagement with the protrusion, then pull it upward, and then move the other inner mold part to the center in the same manner. Then, after releasing the engagement with the projection, the inner mold can be completely removed from the outer mold by pulling it upward.

Further, in this three-piece internal mold, if a center inner mold portion having a straight groove along the diameter line at the outer bottom is used, it is possible to obtain a fractionation petri dish having a fractionation protrusion at the inner bottom. it can. In other words, in the case of a divided petri dish, since the rotation of the inner mold as described above is impossible due to the existence of the fractionation projection, the petri dish having the projection on the inner peripheral wall is formed by using the three-piece internal mold. Becomes possible.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be further described below with reference to the drawings showing embodiments.

FIG. 1 shows an embodiment of a petri dish of the present invention, in which an inclined projection 13 is formed on an inner peripheral wall 11 of the petri dish 1 from an inner bottom 12 to an upper end of the inner peripheral wall 11. is there.

FIG. 2 shows an example of a manufacturing process of the petri dish of the present invention having an inclined projection on the inner peripheral wall. The method of producing the petri dish of the present invention will be described with reference to FIG. After the inner mold 3 having the inclined groove 31 is matched, and then the synthetic resin is injected and solidified, the inner mold 3 is rotated, and the formed inclined protrusion 13 and the inclined groove 31 are screwed together. If the inner mold 3 is lifted off from the outer mold 2 and then the outer mold 2 is removed, an integrally molded body of the petri dish 1 having the inclined projections 13 is obtained.

FIG. 3 shows an example of the manufacturing process of the petri dish of the present invention having a horizontal projection on the inner peripheral wall. The method of producing the petri dish of the present invention will be described with reference to FIG. Side inner mold parts 3a, 3c each having a lateral groove 32
And a divided inner mold formed of a center inner mold part 3b interposed between the side inner mold parts 3a and 3c and having no groove in the outer peripheral part, but having a straight groove 33 along the diameter line in the inner bottom part. After the plastic resin is injected and solidified, the center inner mold part 3b is pulled out upward, and then one side inner mold part 3a is moved to the center part where the space is formed. To release the engagement with the horizontal projection 14 and pull it upward, and then move the other side inner mold part 3c to the center similarly to release the engagement with the horizontal projection 14 and pull it upward. An integrated molded article of the Petri dish 1 having the horizontal projections 14 on the inner peripheral wall and the dividing projections 15 on the inner bottom is obtained.

Next, the effect of preventing the exfoliation of the culture medium when the petri dish of the present invention is used will be described with reference to test examples.

Test Example 1 Using a Petri dish of the present invention and a conventional Petri dish described below, each of which was filled with an agar medium and solidified was used as a sample, dropped on a concrete floor from a height of 70 cm, and whether the medium was peeled off. Was tested. After the drop, the formation of air bubbles between the inner bottom surface of the petri dish and the medium was confirmed, and it was determined that peeling occurred. The results were as shown in Table 1 below.

◎ Petri dish of the present invention used: inner diameter 35.6
mm, 3.8 mm in depth, 0.9 mm in width on the inner peripheral wall, 16.8% of the inner circumference in length, and four inclined projections with an elevation angle of 12 ° are opposed to each other, for a total of four. ◎ Conventional Petri dish used: Same shape and same size as the Petri dish of the present invention except that no inclined projections are present.

[0018]

[Table 1]

From the results of the drop test, it was confirmed that the petri dish of the present invention has a remarkable effect of preventing the exfoliation of the culture medium as compared with the conventional petri dish.

[0020]

According to the present invention, it is possible to provide a petri dish in which the culture medium is not easily peeled off, and it is possible to efficiently produce an integrally molded petri dish having a projection on the inner peripheral wall.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a petri dish of the present invention.

FIG. 2 is a schematic sectional explanatory view showing an example of a manufacturing process of the petri dish of the present invention.

FIG. 3 is a schematic cross-sectional end view illustrating another example of the manufacturing process of the petri dish of the present invention.

FIG. 4 is an explanatory plan view showing a state in which a split inner mold used in a petri dish manufacturing method of the present invention is matched with an outer mold.

FIG. 5 is a schematic cross-sectional explanatory view showing an example in which the conventional type cannot be manufactured.

[Explanation of symbols]

 1: Petri dish 11: Inner peripheral wall 12: Inner bottom surface 13: Inclined projection 14: Horizontal projection 15: Fractionated projection 2: Outer die 3: Inner die 31: Slant groove 32: Lateral groove 33: Straight groove 3a: Side inner die part 3b ： Center inner mold part 3c ： Side inner mold part

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Morisaku Saito 5-39-2 Arakawa-ku, Arakawa-ku, Tokyo Inside Arakawa Jushi Cork Co., Ltd.

Claims (7)

[Claims] 1. A petri dish wherein a projection is formed on an inner peripheral wall. 2. The petri dish according to claim 1, wherein the projection is a slanting projection obliquely upward from the inner bottom. 3. The petri dish according to claim 2, wherein the petri dish is an inclined projection having an output width of 0.5 to 5.0 mm, a length of 10 to 20% of the inner circumference, and an elevation angle of 10 to 30 °. 4. The number of projections formed is 2 to 4.
The petri dish according to any one of the above items 3. 5. A method for producing a petri dish having an inclined projection on an inner peripheral wall, wherein injection integral molding of a synthetic resin is performed using an outer die and an inner die having an oblique groove on an outer peripheral portion. 6. An outer mold, two side inner mold parts having a circular groove, a vertical groove or a lateral groove in an outer peripheral part, and one center having no groove in an outer peripheral part used between the side inner mold parts. A method for manufacturing a petri dish having a hemispherical, vertical or horizontal projection on an inner peripheral wall thereof, wherein injection integral molding of a synthetic resin is performed using a divided inner mold composed of a mold portion. 7. The method for producing a petri dish according to claim 6, wherein the inner mold part having a straight groove along the diameter line at the outer bottom is used as the center inner mold part.