JPH11178693A - Half-split chopsticks and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate all split parts of half-split chopsticks equally by applying a moderate force to each part thereof in use while keeping the parts thereof from being divided under any vibration or the like prior to the use thereof. SOLUTION: Half-split chopsticks 1 have split parts 2 and 3 comprising a thermoplastic material such as polypropylene. The split parts 2 and 3 are integrally interlinked at each lengthwise one end part 2a or 3a thereof by a link part in a predetermined fixed area within respective opposed faces 4 and 5. The predetermined fixed areas are selected at positions near the central part between both width-wise end parts of the opposed face 4 and 5 while being deviated in the direction of being isolated from the length-wise other end parts 2b and 3b of the respective split parts 2 and 3, not from the center of the drawing of the respective opposed faces 4 and 5. As a result, when a force is applied to the split parts 2 and 3 in the direction of isolating them from each other, a larger tearing force than that applied on the split parts 2 and 3 is generated at the link part 6 causing the link part 6 to be easily severed thereby enabling separating of the individual split parts 2 and 3 almost equally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to disposable chopsticks used for meals and the like and a method for producing the same.

[0002]

2. Description of the Related Art A typical prior art is disclosed in Japanese Patent Laid-Open No. 6-72.
No. 36 and JP-A-6-169835. These prior art disposable chopsticks are synthetic resin disposable chopsticks formed by extrusion molding, and include a pair of disposable chopsticks tapering from one axial end to the other axial end, and each disposable chopstick is formed by a pair of disposable chopsticks. It is manufactured in a state where the opposing surfaces facing each other are integrally connected at one end in the axial direction. In such disposable chopsticks, a user grasps an arbitrary position between the center part between both ends in the axial direction of the disposable chopstick part and the other end part in the axial direction with a finger, and separates the disposable chopstick parts from each other. By applying a force to separate the chopsticks in the direction in which the chopsticks are separated, the connecting portions at the one axial end of each chopstick can be broken to separate the chopsticks for use. Such disposable chopsticks are manufactured by extruding a molten synthetic resin from a die provided with a pair of discharge holes. At this time, the synthetic resin in a semi-molten state extruded from the die, since the extrusion pressure is released immediately after leaving each discharge hole, when the take-up speed of the synthetic resin is low, the resin slightly swells and exits each discharge hole. The semi-melted synthetic resins come into contact with each other and are connected. By increasing the take-up speed of the semi-molten synthetic resin extruded from each discharge hole, the cross-sectional area of the semi-solid synthetic resin perpendicular to the axis can be made smaller than the opening area of each discharge hole. The take-up speed is periodically increased and decreased, and the cycle is set to correspond to the length of two sets of chopsticks. In this manner, the synthetic resin is extruded while the cross-sectional area perpendicular to the axis in the longitudinal direction is alternately increased and decreased at a constant cycle, and two rod-shaped bodies having a pair of disposable chopsticks are formed. These two rods are connected at a portion having the largest cross-sectional area perpendicular to the axis. These two rods are cut at a portion having the largest cross-sectional area at right angles to the axis and at a portion having the smallest cross-sectional area at right angles to the axis, thereby continuously producing a plurality of synthetic resin chopsticks.

[0003]

In such a prior art disposable chopstick, since one end in the longitudinal direction of each disposable chopstick portion is integrally connected on the entire surface of each opposing surface, a large force is required when dissecting the disposable chopsticks. Needs to be applied to each disposable chopstick portion. When the connecting strength of the connecting portions of the chopsticks is too large, one of the chopsticks may be broken at an intermediate portion in the axial direction, or each of the chopsticks may be a connecting portion, that is, the split chopsticks may not be almost evenly broken. In such a case, there is a problem that it becomes difficult to use each disposable chopstick portion, and it becomes difficult to hold articles such as food. Especially when the shape of each chopsticks part is extremely different when separated,
New disposable chopsticks have to be used, which wastes a lot of disposable chopsticks, which is not economical, increases waste and causes environmental problems.

[0004] Further, if the connecting strength of the connecting portions of the chopsticks is too small, the chopsticks are undesirably separated due to vibrations during the manufacture, packing, and transportation of the chopsticks. However, there is a problem that the quality is lowered and the quality as a product is lowered.

In the above-mentioned conventional chopsticks, each chopstick portion is formed by extrusion molding, which has a simple shape whose sectional shape does not change in the axial direction, has good productivity, and can be mass-produced. In extrusion molding, there is a limit in improving the molding accuracy, and the shape accuracy of the disposable chopsticks deteriorates. That is, in the extrusion molding, when cutting the two rods, the cutting position is different for each chopstick, and the shape of each chopstick and the area where the connecting portion of each chopstick is formed is different for each product. As a result, there is a problem that a large number of disposable chopsticks having a high precision and a uniform shape cannot be continuously produced. Although other molding methods, such as injection molding, can be easily considered to solve this problem, injection molding has a problem that productivity is lower than extrusion molding.

Further, the above-mentioned conventional chopsticks are made of a synthetic resin, and have a problem that they are not decomposed by soil microorganisms in soil even if they are discarded as garbage, for example, landfilled, which adversely affects the environment. is there.

An object of the present invention is to prevent each chopstick portion from being separated by a force necessarily acting on each chopstick portion before use during manufacturing, packing, transportation, and the like, and to hand-clasp each chopstick portion during use. It is an object of the present invention to provide a disposable chopstick which can separate the disposable chopstick portions almost equally by applying a moderate force to the extent that the disposable chopsticks can be actuated.

Another object of the present invention is to provide a disposable chopstick that can be disposed after use with less or no adverse effects on the environment.

Still another object of the present invention is to provide a disposable chopstick which is not separated by a force acting on the disposable chopsticks before use during manufacturing, packing, transportation, etc. The disposable chopsticks that can be produced with high precision and high shape stability can be separated from each disposable chopstick part almost equally by applying an appropriate force that can be applied to the parts by fingers etc. It is to provide a manufacturing method.

[0010]

SUMMARY OF THE INVENTION The present invention has a pair of chopstick portions made of a thermoplastic material, and one longitudinal end of each chopstick portion has a predetermined length in each of opposing surfaces facing each other. The predetermined area is connected integrally in a certain area, and the predetermined area is near the center between both ends in the width direction perpendicular to the longitudinal direction of each chopstick portion on each opposing face, and each chopstick is more than the centroid of each opposing face. Disposable chopsticks are selected at a position shifted in a direction away from the other longitudinal end of the portion.

According to the present invention, the pair of chopsticks is made of a thermoplastic material, and one end of each chopstick in the longitudinal direction is integrally connected to a predetermined area in the opposing surfaces. I have. This predetermined area is located near the center between the widthwise ends of each of the opposing surfaces perpendicular to the longitudinal direction of each chopstick portion, and further away from the centroid of each opposing surface than the other longitudinal end of each chopstick portion. This is a region shifted in the direction of movement. When a force is applied in a direction that separates the chopsticks from each other, the ridges near each of the opposing surfaces of the chopsticks and one end face in the longitudinal direction of the chopsticks that intersect each other. Each disposable chopstick is angularly displaced as a fulcrum. by this,
A splitting force greater than the force applied to each of the chopstick portions is applied to a portion where the chopstick portions formed at one longitudinal end of each of the chopstick portions are continuously connected. Further, the part where the chopsticks are integrally connected is not a whole area of each opposing surface at one longitudinal end of each chopstick but a partial area thereof.
In this area, when a force is applied in a direction to separate the chopstick portions from each other, the cross-sectional area perpendicular to the direction in which the force acts is smaller than the remaining portion, and the stress to the force applied to the respective chopstick portions is reduced. Becomes larger than the rest. Therefore, the chopsticks are separated into the chopstick portions at portions where the chopstick portions are continuously connected. In this way, the chopsticks can be easily divided at a part where they are integrally connected, and the chopsticks can be separated substantially evenly. Furthermore, by making the length of the portion where each chopstick portion is integrally connected in the direction along the longitudinal direction of each chopstick portion sufficiently large relative to the thickness of the portion where each disposable chopstick portion is integrally connected, during manufacturing, packing and transportation It is possible to prevent a portion where the chopstick portions are integrally connected from being broken due to vibration or the like at the time. Furthermore, since the portion where each disposable chopstick part is continuously connected is selected as a predetermined area on each of the opposing surfaces, even if mass production of disposable chopsticks is performed, any part of the disposable disposable chopsticks is continuously connected to any disposable chopsticks. Is formed in a predetermined area, as in extrusion molding, the area where the connecting portion of each chopstick is formed is different for each product, and the connecting strength of the connecting portion is different for each product. No trouble occurs.

Further, according to the present invention, the material having thermoplasticity comprises:
It is characterized by being made of any one of polypropylene, polycarbonate and polystyrene.

According to the present invention, since the thermoplastic material is made of any one of polypropylene, polycarbonate and polystyrene, it has good moldability and has sufficient mechanical strength to be used as chopsticks, Disposable chopsticks with stable product quality can be manufactured.

When a block copolymer of polypropylene is used as the polypropylene, unfilled polycarbonate is used as the polycarbonate, and impact-resistant polystyrene is used as the polystyrene, all of the above polypropylene, polycarbonate and polystyrene have good moldability. Stable mechanical, thermal and chemical properties. Even when chopsticks are manufactured using any one of the above polypropylene, polycarbonate, and polystyrene, the mechanical, thermal, and chemical performances of the chopsticks are stable. Therefore, even if mass-produced disposable chopsticks, the quality of the product is stable. As described above, the chopsticks made of any one of the above polypropylene, polycarbonate and polystyrene are stable in quality as a product. Therefore, (a) mechanical performance according to the shape of the connecting portion of each chopstick, for example, (B) the thermal performance of each disposable chopstick, such as the ability of each disposable chopstick to be thermally deformed at the operating temperature, and (c) the performance of each disposable chopstick when dropped from a certain height. Chemical performance, even when using disposable chopsticks to pinch foods such as pickled plums and pickled vegetables, each disposable chopstick has various performances such as the ability to achieve acid resistance and alkali resistance that does not cause a chemical change. Many disposable chopsticks can be manufactured.

Further, according to the present invention, the material having thermoplasticity comprises:
It is characterized by comprising a biodegradable material containing at least a natural polymer resin, a natural polymer compound and a mineral.

According to the present invention, the thermoplastic material is composed of a biodegradable material containing at least a natural polymer resin, a natural polymer compound and a mineral. Degraded by soil microorganisms in soil, minerals are originally contained in soil and are harmless even if scattered in soil. Therefore, even after use of the disposable chopsticks, even if they are disposed of as garbage, for example, landfilled, they can be disposed with less or no adverse effects on the environment, for example, soil pollution and water pollution.

Further, the present invention is characterized in that a powder having a melting point higher than that of the thermoplastic material is mixed with the thermoplastic material.

According to the present invention, the thermoplastic material is mixed with a powdery material composed of a material having a higher melting point than the thermoplastic material, so that the thermoplastic material can be melted. Without melting the powder, the powder can be dispersed in the molten thermoplastic material. Therefore, the surface of the disposable chopstick made of a thermoplastic material mixed with the powder and granules has irregularities due to the powder and granules, and the disposable chopstick can be provided with an anti-slip effect. In addition, by mixing the granules with the thermoplastic material, the amount of the thermoplastic material required for molding is determined by the mixing amount of the granules for the disposable chopsticks of the same dimensions where the granules are not mixed. Can be reduced by minutes. Furthermore, when a non-combustible substance such as calcium carbonate powder is used as the granules, the amount of heat generated when the chopsticks made of the thermoplastic material mixed with the granules is incinerated is made of only the thermoplastic material. The amount of heat generated when the chopsticks are incinerated can be reduced.

The present invention is also characterized in that an antibacterial agent is mixed with the thermoplastic material.

According to the present invention, since the antibacterial agent is mixed with the thermoplastic material, antibacterial properties can be imparted to the disposable chopsticks. Therefore, even if the disposable chopsticks are not used for a long period of time, the propagation of mold and germs can be prevented, which is hygienic.

According to the present invention, there is provided a first mold in which a pair of first grooves extending substantially in parallel and communicating with each other at one end in the longitudinal direction are formed adjacent to each other. A pair of second grooves extending substantially parallel to each other and communicating with each other at one end in the longitudinal direction are formed adjacent to each other, and the pair of second grooves are connected to the gates communicating with each other at one end in the longitudinal direction. And a second mold in which a sprue for guiding the material having thermoplasticity to the runner and a sprue for guiding the material having thermoplasticity to the runner are prepared, and each first groove and each second groove oppose each other. After clamping the first mold and the second mold in this state, the molten thermoplastic material is injected into the first and second grooves from the sprue through the runner and the gate, and the molten heat is injected. The first and second grooves are filled with a plastic material, and the first and second grooves are filled. After the molten thermoplastic material filled in the groove is cured, the mold clamping between the first mold and the second mold is released, and a pair of disposable chopsticks made of a thermoplastic material is provided. In a state where disposable chopsticks integrally connected to each other in a predetermined region in each of opposing surfaces opposing each other at one longitudinal end of the portion are engaged with the inner surface forming the first concave groove,
A method for manufacturing disposable chopsticks, comprising: moving a mold in a direction away from a second mold, and extruding the disposable chopsticks away from the first mold.

According to the present invention, a first mold in which a pair of first grooves is formed and a second mold in which a pair of second grooves, a gate, a runner and a sprue are formed are prepared. The first mold and the second mold are clamped in a state where the first grooves and the second grooves face each other. After that, the first and second grooves are filled with a material having a molten thermoplastic, and the material having a molten thermoplastic filled with the first and second grooves is cured, and has a pair of disposable chopsticks, Manufacture disposable chopsticks that are integrally connected at one longitudinal end of each disposable chopstick portion. With the disposable chopsticks engaged with the inner surface forming the first groove, the first mold is
Since the disposable chopstick is moved away from the mold and the disposable chopstick is pushed out of the first mold and detached, one of the disposable chopstick portions of the disposable chopstick is engaged with the inner surface of the first mold forming the first concave groove. By moving the first mold in a direction away from the second mold while the other of the chopstick portions of the chopsticks is engaged with the inner surface of the second mold forming the second concave groove, The disposable chopsticks can be securely separated from each other without any trouble such as splitting at the portions where the disposable chopsticks are integrally connected, or each disposable chopstick being engaged with the second groove to remove the disposable chopsticks from the second mold. It can be extruded and released from the mold.

The present invention also provides an imaginary plane including the first end face in a region surrounded by the first end face at one end in the longitudinal direction of the inner face extending in the longitudinal direction of each first groove of the first mold. A first raised portion protruding toward the other end in the longitudinal direction is formed, and is surrounded by a second end surface of one end in the longitudinal direction of the inner surface extending in the longitudinal direction of each second concave groove of the second mold. Is formed with a second raised portion protruding from the virtual plane including the second end face toward the other end in the longitudinal direction, and is injection-molded using the first and second molds.

According to the present invention, the area surrounded by the first end face at one end in the longitudinal direction of the inner surface extending in the longitudinal direction of each first concave groove of the first mold includes the first end face. A first raised portion protruding from the plane toward the other end in the longitudinal direction is formed, and is surrounded by a second end surface at one longitudinal end of an inner surface extending in a longitudinal direction of each second concave groove of the second mold. In the region, a second raised portion protruding from the virtual plane including the second end surface toward the other end in the longitudinal direction is formed, and the first and second molds are used for injection molding, so that the first and second molds are formed. A recess is formed at one longitudinal end of each chopstick portion of the chopstick corresponding to the second raised portion, and a gate piece formed by each gate is integrally connected to the bottom of each recess.
When the disposable chopsticks are pushed out of the first mold and separated, a bending moment due to the weight of the disposable chopsticks acts on each gate piece, and a bending stress is generated by the bending moment. This bending stress is applied to the bottom of each recess of the gate piece. Each gate piece breaks concentrated at each base end part, that is, at the base of each gate piece,
Each gate piece and each chopstick portion are separated.

Since each chopstick portion is separated from each gate piece by its own weight when the chopstick portion is extruded from the first mold and is separated, the chopstick portion is manually separated from each gate piece. Can be omitted, and productivity can be improved. Further, since each gate piece is broken at a base end portion connected to the bottom of each recess of each gate piece, the broken portion of each gate piece is formed by the first end face of each first groove and the second recess. The broken portion does not protrude outside from an imaginary plane including the end surface of each longitudinal end of each chopstick portion corresponding to the second end surface of the groove, and the broken portion is inconspicuous.

[0026]

FIG. 1 is a plan view of a disposable chopstick 1 according to an embodiment of the present invention, FIG. 2 is a sectional view showing an enlarged section 2 of FIG. 1, and FIG. Section line II
FIG. 4 is a sectional view taken along line I-III, and FIG. 4 is a sectional view taken along line IV-IV of FIG.

The chopsticks 1 have a pair of chopstick portions 2 and 3 made of a thermoplastic synthetic resin, for example, polypropylene, which is a thermoplastic material. One end 2a, 3a of each disposable chopstick portion 2, 3 in the longitudinal direction (the left-right direction in FIG. 1) is formed in a substantially rectangular parallelepiped shape, and one end 2a, 3a of each disposable chopstick portion 2, 3 in the longitudinal direction is formed. The remaining part other than the substantially rectangular parallelepiped part is formed substantially in the shape of a column, and the other end 2 in the longitudinal direction is formed.
b and 3b are formed in a tapered shape. The longitudinal ends 1a, 3a of the chopstick portions 2, 3 are integrally connected by a connecting portion 6 in a predetermined area of the opposing surfaces 4, 5 facing each other.

The connecting portion 6 is formed in a substantially rectangular sheet shape and is made of the same material as each of the chopstick portions 2 and 3. The predetermined area includes both ends 4 in the width direction perpendicular to the longitudinal direction of each of the chopstick portions 2 and 3 on each of the opposing surfaces 4 and 5.
a, 4b; near the center 4c, 5c between 5a, 5b, and away from the center of each of the opposing surfaces 4, 5 in the direction away from the other longitudinal ends 2b, 3b of the chopstick portions 2, 3 Selected position. That is, the connecting portion 6 is formed at the center portions 4c, 5 between both ends 4a, 4b in the width direction of the opposing surfaces 4, 5;
It is provided near c. One longitudinal end 6a of the connecting portion 6
Are provided on the other end 2b, 3b side of each chopstick portion 2, 3 in the longitudinal direction with respect to the one end portion 2a, 3a in the longitudinal direction of each chopstick portion 2, 3. The other end 6b in the longitudinal direction of the connecting portion 6 is provided closer to the other end 2b, 3b in the longitudinal direction of each of the chopstick portions 2, 3 than the centroid of each of the opposing surfaces 4, 5. Both ends 6a and 6b in the longitudinal direction of the connecting portion 6 are formed so as to be recessed toward the opposite longitudinal ends 6b and 6a. The longitudinal length L3 of the connecting portion 6 is 70 to 150 of the thickness t of the connecting portion 6.
Times, preferably about 100 to 120 times.

Here, as an example of the dimensions of the chopsticks 1, the length L1 in the longitudinal direction of each of the chopstick portions 2, 3 is, for example, 200 m.
m, and one end 2 of each disposable chopstick portion 2, 3 in the longitudinal direction.
The length B1 in the width direction of a and 3a is, for example, about 6 mm. The height H1 of the longitudinal ends 1a, 3a of the chopstick portions 2, 3 is, for example, about 5 mm. The diameter D1 in the vicinity of the center between the longitudinal ends 2a, 2b; 3a, 3b of each of the chopstick portions 2, 3 is, for example, about 5 mm. One end 2a, 3a in the longitudinal direction of each disposable chopstick part 2, 3
The length L2 in the longitudinal direction of the portion formed into a substantially rectangular parallelepiped is
For example, it is about 15 mm. The longitudinal length L3 of the connecting portion 6 is, for example, about 5 mm. The length B2 in the width direction of the connecting portion 6 is, for example, about 1 mm. The thickness t of the connecting portion 6 is, for example, about 0.05 mm. The end face 7 of each longitudinal end 1a, 3a of each disposable chopstick part 2, 3,
L4 between the end portion 8 and one end 6a of the connecting portion 6 in the longitudinal direction.
Is, for example, about 4 mm. The distance L5 between one end 4a of the facing surface 4 in the width direction (vertical direction in FIG. 3) and one surface 6c of the connecting portion 6 is, for example, about 2.7 mm.

In order to split the chopsticks 1, an arbitrary position between the center between the longitudinal ends 2 a, 2 b; 3 a, 3 b of each chopstick part 2, 3 and the other end 2 b, 3 b in the longitudinal direction is finger-operated. In the state of being gripped with, a force is applied in a direction for separating the chopstick portions 2, 3 from each other. Thereby, the ridges 9 and 10 of the opposing surfaces 4 and 5 of the chopstick portions 2 and 3 and the end surfaces 7 and 8 of the longitudinal end portions 2a and 3a of the chopstick portions 2 and 3 intersecting with the opposing surfaces 4 and 5 respectively abut. Each disposable chopstick part 2, 3 is the ridge 9,
Angular displacement occurs around 10 as a fulcrum. According to the principle of leverage, the connecting portion 6 of each of the chopstick portions 2 and 3 has
3 is applied to the connecting portion 6.
The largest splitting force acts on the other end 6b side in the longitudinal direction. The connecting portion 6 of each of the chopstick portions 2, 3 is not the entire surface of each of the opposing surfaces 4, 5 at one of the longitudinal end portions 2a, 3a of each of the chopstick portions 2, 3, but a partial region thereof. In this area, when a force is applied in a direction in which the chopstick portions 2, 3 are separated from each other, the cross-sectional area perpendicular to the direction in which the force acts is smaller than the remaining portion, and the respective chopstick portions 2, 3 The stress for the applied force is greater than the rest. Since the other end 6b in the longitudinal direction of the connecting portion 6 is formed to be recessed toward the one end 6a in the longitudinal direction, the maximum splitting force causes the other end 6b in the longitudinal direction of the connecting portion 6 and each chopstick portion 2, Stress concentrates on the central portion m1 between the three portions, and the vicinity of the central portion m1 of the other longitudinal end 6b of the connecting portion 6 is broken and a crack is generated. A substantially uniform splitting force in mode I referred to as a fundamental mode of the crack plane displacement acts on this crack. At the tip of the crack, the connecting part 6
A symmetrical plastic zone is formed with respect to a plane parallel to the plane of FIG. 4 which is included in the longitudinal axis passing through the central portion m1 of FIG. Since the splitting force acts on the crack with its temporal change being small,
Cracks propagate along the plane of symmetry of this plastic zone. Therefore, the connecting portion 6 is broken so as to be divided on both sides of the one plane including the central portion m1.

As described above, the connecting portion 6 is substantially equally divided, and the fragment of the connecting portion 6 is divided into the disposable chopstick portions 2,
Only slightly projecting from 3 and this fragment is inconspicuous. The connecting portion 6 is provided in the vicinity of central portions 4c, 5c between the opposite ends 4a, 4b; 5a, 5b of the opposing surfaces 4, 5, and one end 6a in the longitudinal direction of the connecting portion 6 is connected to each chopstick portion. Since each of the chopstick portions 2, 3 is provided at a distance from the other longitudinal end 2 b, 3 b of each of the chopstick portions 2, 3 with respect to the longitudinal end 2 a, 3 a of each of the chopstick portions 2, 3, The disposable chopsticks 1 do not break when one of the ends 2a, 3a is connected to the connecting portion 6. Further, in the connecting portion 6, the chopstick portions 2, 3 pass through a central portion 6c between both ends 6a, 6b in the longitudinal direction of the connecting portion 6 due to vibrations during manufacturing, packing, and transportation, and are perpendicular to the longitudinal direction. Angular displacement about an axis extending in a certain direction, a torsional moment acts on the connecting portion 6. At this time, as the longitudinal length L3 of the connecting portion 6 increases, the shear stress generated in the connecting portion 6 decreases. Therefore, the length L3 in the longitudinal direction of the connecting portion 6 is selected to be about 100 to 120 times the thickness t of the connecting portion 6, so that the shear stress generated by the torsional moment is reduced, and the shearing stress due to manufacturing, packing, transportation, etc. The connecting portion 6 can be prevented from breaking.

In this manner, the connecting portion 6, in which the chopstick portions 2, 3 are integrally connected, can be easily and evenly divided, and the chopstick portions 2, 3 can be evenly separated. Also, since the connecting portion 6 is selected in a predetermined area of each of the opposing surfaces 4 and 5, even if the chopsticks 1 are mass-produced,
The connecting portion 6 is formed in the predetermined area with respect to an arbitrary disposable chopstick 1. Therefore, unlike the extrusion molding, the region where the connecting portion of each of the chopstick portions 2 and 3 is formed differs for each product, and the problem that the connecting strength of the connecting portion 6 differs for each product does not occur.

FIG. 5 is a view for explaining a method of manufacturing the chopsticks 1, FIG. 6 is a cross-sectional view showing a state where each of the chopstick portions 2, 3 is engaged with the first groove 23, and FIG. FIG. 8 is an enlarged plan view showing a part of the second mold 22, and FIG.
FIG. 4 is an enlarged cross-sectional view showing the vicinity of one longitudinal end of first and second concave grooves 23 and 24 in a state where the mold and a second mold 22 are clamped. FIG. 5A is a diagram showing a state in which the first mold 21 and the second mold 22 are clamped, and FIG.
FIG. 4 is a view showing a state in which mold clamping between the first mold 21 and the second mold 22 has been released.

The chopsticks 1 are formed by injection molding.
In order to form the disposable chopsticks 1, a screw-type injection molding machine (hereinafter, sometimes simply referred to as a molding machine) and a first mold 21 are used.
And a second mold 22 are prepared. A pair of first concave grooves 23 extending substantially in parallel and communicating with each other at one longitudinal end are formed adjacent to the first mold 21. The second mold 22 is formed with a pair of second concave grooves 24 extending substantially parallel to the first concave grooves 23 and communicating with each other at one longitudinal end. The second mold 22 is formed with a gate 25, a runner 26, and a sprue 27 that communicate with the second grooves 24 at one end in the longitudinal direction. Gate 25
Runner 26 for guiding molten polypropylene to gate 25
Communicate with The runner 26 communicates with a sprue 27 that guides the melted polypropylene to the runner 26.

The first mold 21 has a bottom surface 2 of the first groove 23.
8 and one surface 2 of the first mold 21 facing the second mold 22
An insertion hole 31 is formed over the other surface 30 opposite to the surface 9. A disposable chopstick 1 as a molded product is extruded into the insertion hole 31, and an extrusion pin 32 extending in the longitudinal direction is inserted. The extruding pin 32 is formed on the extruding rod 3 fixed to the molding machine at one longitudinal end 32 a on the side protruding from the first mold 21.
3 and is integrally fixed to an extruding plate 34 which can be brought into contact therewith. First
A compression coil spring 35 is disposed between the mold 21 and the extrusion plate 34 so as to be coaxial with the axis of the extrusion pin 32. The first and second molds 21 and 22 are formed with a cooling water passage 36 to which cooling water for cooling the first and second molds 21 and 22 is supplied.

The pair of first concave grooves 23 communicate with each other at one longitudinal end by a first communication groove 37. The pair of second concave grooves 24 communicate with each other at one end in the longitudinal direction by a second communication groove 38. Thus, the cavity 39 is formed by the first groove 23 and the first communication groove 37 and the second groove 24 and the second communication groove 38. The space formed by each of the first groove 23 and the second groove 24 in the cavity 39 is defined by an imaginary substantially rectangular parallelepiped surface at one longitudinal end thereof, and the remaining space excluding the virtual substantially rectangular parallelepiped portion at one longitudinal end is provided. The portion is formed in an imaginary substantially cylindrical shape, and is defined by an imaginary substantially cylindrical surface whose other end in the longitudinal direction is tapered. The first groove 23 and the second groove 24 form the cavity 39 by a second mold more than the virtual plane including the axis of each virtual cylinder formed by the first groove 23 and the second groove 24. At a position shifted to the side of the imaginary cylinder, for example, at a position where the ratio of the length in the diameter line direction between the first mold 21 side and the second mold 22 side of the virtual cylinder is 5.5: 4.5. It is formed by dividing. Here, an opening width B3 perpendicular to the longitudinal direction of the opening of the first concave groove 23 is, for example, about 4.97 mm. Here, the size of the cavity 39 is set to the size of the size of the disposable chopstick 1 plus an amount considering the heat shrinkage of the disposable chopstick 1.

As shown in FIGS. 7 and 8, one end of the inner surface 41 extending in the longitudinal direction of each first groove 23 of the first mold 21 has a first end surface perpendicular to the inner surface 41. 4
2 are formed. A first spherical raised surface 43 which is a part of a spherical surface protruding from an imaginary plane including the first end surface 42 toward the other longitudinal end is provided in a region surrounded by the first end surface 42. A raised portion 44 is formed. A second end surface 47 perpendicular to the inner surface 46 is provided at one longitudinal end of an inner surface 46 extending in the longitudinal direction of each second groove 24 of the second mold 22.
Is formed. In a region surrounded by the second end surface 47, a second spherical raised surface 48 which is a part of a spherical surface protruding from the virtual plane including the second end surface 47 toward the other end in the longitudinal direction is provided. A raised portion 49 is formed. The gate 25 is formed at the second raised portion 49 and communicates the second groove 24 with the runner 26.

The first mold 21 is attached to a movable die plate of the molding machine, and is provided so as to be movable in a direction approaching the second mold 22 and in a direction away from the second mold 22. The second mold 22 is
It is fixed to the fixed die plate of the molding machine. First mold 21
The second mold 22 is cooled to 20 to 100 ° C., preferably 50 ° C. by the cooling water flowing through the cooling water passage 36. The temperature of the molten polypropylene injected from the nozzle of the molding machine is 180 to 260 ° C, preferably 180 ° C.
Set to about. Injection pressure is 500 ~ 1500kg
/ Cm ² , preferably about 900 kg / cm ² . The polypropylene is preliminarily dried at about 80 ° C. for about 5 hours before injection molding. Further, the melt index of polypropylene is about 8.

In FIG. 5A, the first mold 21 and the second
The mold 22 is clamped with a pressure greater than the injection pressure of the molten polypropylene injected into the cavity 39 in a state where the first grooves 23 and the second grooves 24 face each other. Next, the molten polypropylene is injected from the sprue 27 into the cavity 39 via the runner 26 and the gate 25, and the cavity 39 is filled with the molten polypropylene. At this time, since the molten polypropylene has good fluidity, although the space formed by the first and second communication grooves 37 and 38 is a very narrow space, the space is surely filled with the molten polypropylene.
Therefore, the first and second concave grooves 23 and 24 form the respective chopstick portions 2 and 3 of the chopstick 1, and the first and second communication grooves 37 and 38 form the connecting portion 6.

Next, after the molten polypropylene filled in the cavity 39 is cooled and hardened, the mold clamping between the first mold 21 and the second mold 22 is released. That is, the first mold 21 moves in a direction away from the second mold 22. At this time, there is a pair of chopstick portions 2, 3 made of polypropylene molded with the first and second concave grooves 23, 24, and they are opposed to each other at one longitudinal end 2a, 3a of each chopstick portion 2, 3. The chopsticks 1 integrally connected by the connecting portions 6 in predetermined regions in the opposing surfaces 4 and 5 are engaged with the inner surface 41 forming the first groove 23. This means that, as shown in FIG. 6, one surface 29 of the first mold 21 is larger than an imaginary plane including the axis 4a of each of the chopstick portions 2 and 3 in the second mold 22.
The opening width B3 perpendicular to the longitudinal direction of the opening of the first concave groove 23 is set to be shifted to the side, so that each of the chopstick portions 2, 3
Is smaller than the diameter D1, thereby indicating that each disposable chopstick portion 2, 3 is engaged with the inner surface 41 forming each first concave groove 23. Therefore, one of the chopstick portions 2, 3 of the chopstick 1 is engaged with the inner surface 41 forming the first concave groove 23 of the first mold 21, and the other of the chopstick portions 2, 3 of the chopstick 1 is Inner surface 46 of second mold 22 forming second concave groove 24
The first mold 21 is moved in a direction away from the second mold 22 in a state of being engaged with
The connecting portion 6 which is integrally connected to the second mold 2 is cut off, and the chopstick portions 2 and 3 are engaged with the second concave grooves 24 so that the chopsticks 1 are connected to the second mold 2.
The disposable chopsticks 1 can be reliably pushed out of the first mold 21 and detached without causing troubles such as troublesome removal from the second mold 2.

Next, the disposable chopsticks 1 are extruded from the first mold 21 and separated. As shown in FIG. 5 (2), when the first mold 21 moves in a direction away from the second mold 22 and the first mold 22 moves to the vicinity of the retreat limit, the pushing rod 33 The pushing plate 34 comes into contact, and only the pushing plate 34 is prevented from retreating. Therefore, when the first mold 21 moves further away from the second mold 22,
The extrusion plate 34 is extruded toward the second mold relative to the first mold 21, and the extrusion pin 32 projects from the bottom surface 28 of the first groove 23. The opening width of each first concave groove 23 is provided smaller than the diameter of each split chopstick portion 2, 3. The difference 2d between the diameter D1 of each of the chopstick portions 2, 3 and the opening width B3 is set within the elastic deformation range of polypropylene. Therefore, when the other end 32b in the longitudinal direction of the push pin 32 protrudes from the bottom surface 28 of each first groove 23, the other end in the longitudinal direction of the push pin 32 contacts the outer peripheral surface of each of the chopstick portions 2, 3, and By moving the first mold 21 in the direction away from the second mold 22, each chopstick portion 2, 3 is pushed out from each first groove 23. At this time, as described above, since the difference 2d between the diameter D1 of each chopstick portion 2, 3 and the opening width B3 is set within the elastic deformation range of the polypropylene, each chopstick portion 2, 3 is formed by each first groove. When it is pushed out of the first groove 23, it elastically deforms inward, but after it is pushed out of the first groove 23, it is restored by the elasticity of the polypropylene, which may damage each of the chopstick portions 2, 3. Can be prevented.

Next, when the first mold 21 moves in the direction approaching the second mold 22 in order to clamp the first mold 21 and the second mold 22, the extruding plate 34 is compressed by a compression coil spring. The pushing pin 33 is urged by the elastic restoring force of 35 and the pushing pin 32 retreats relatively to the first mold 21. When the compression coil spring 35 is in a natural state, the pushing plate 34 is separated from the pushing rod 35. Thus, the push pin 32
Returns to the return position shown in FIG.

An imaginary plane including the first end face 42 is provided in a region surrounded by the first end face 42 at one longitudinal end of the inner face 41 extending in the longitudinal direction of each first groove 23 of the first mold 21. Raised portion 44 protruding toward the other longitudinal end from the first
Is formed in a region surrounded by the second end surface 47 at one end in the longitudinal direction of the inner surface 46 extending in the longitudinal direction of each second concave groove 24 of the second mold 22, including the second end surface 47. A second raised portion 49 projecting from the plane toward the other longitudinal end
Is formed, and injection molding is performed using the first and second molds 21 and 22, so that the first and second raised portions 44 and 4 are formed.
9 have concave portions 50, 51 each having a part of a spherical surface at one longitudinal end 2a, 3a of each of the chopstick portions 2, 3 of the chopstick 1.
Are respectively formed, and the bottoms 52,
Reference numeral 53 denotes a gate piece 5 formed by each gate 25.
4, 55 are integrally connected. When the disposable chopsticks 1 are pushed out of the first mold 21 and detached, the gate pieces 54, 55
, A bending moment due to the weight of the disposable chopstick 1 acts, and the bending moment generates a bending stress. The bending stress is applied to the bottoms 52, 51 of the recesses 50, 51 of the gate pieces 54, 55.
The gate pieces 54, 55 are broken at the base end portions 56, 57 connected to 53, and the gate pieces 54, 55 and the chopstick parts 2, 3 are separated.

As described above, when each of the chopstick portions 2, 3 is extruded from the first mold 21, and is separated from the gate pieces 54, 55 by its own weight, each of the chopstick portions 2, 3 is separated from each other. The step of manually separating from the gate pieces 54 and 55 can be omitted, and the productivity can be improved. Also, each of the gate pieces 54, 55 is provided with a base end portion 56, which is connected to the bottom 52, 53 of each of the recesses 50, 51 of the gate piece.
57, the broken portions of the gate pieces 54 and 55 correspond to the first end faces 42 of the first grooves 23 and the second end faces 47 of the second grooves 24, respectively. The broken portions do not protrude outside from an imaginary plane including the end surfaces 7 and 8 of the longitudinal end portions 2a and 3a of the portions 2 and 3, and the broken portions are not conspicuous.

Since the thermoplastic synthetic resin, which is a thermoplastic material, is made of polypropylene, it has good fluidity, easily flows into the first and second communication grooves 37, 38, and is connected to the connecting portions 6 of the chopstick portions 2, 3. Can be reliably formed. Thereby, molding defects of the disposable chopsticks 1 manufactured by injection molding are reduced, and the productivity of the disposable chopsticks 1 is improved. In addition, since polypropylene is easily available and has high mechanical strength, it is possible to manufacture disposable chopsticks 1 that are inexpensive and have sufficient mechanical strength to be used as chopsticks.

In the embodiment of the present invention, the thermoplastic synthetic resin, which is a material having thermoplasticity, is made of polypropylene. In another embodiment of the present invention, the thermoplastic synthetic resin is made of polycarbonate or polystyrene. It may consist of any one. When the thermoplastic synthetic resin is made of polycarbonate, the temperature of the molten polycarbonate injected from the nozzle of the molding machine is 250-300 ° C., preferably 28
The temperature is set to about 0 ° C., the temperature of the first and second molds 21 and 22 is set to about 80 to 130 ° C., preferably about 90 ° C., and the injection pressure is set to 800 to 2000 kg / cm ² , preferably 800 kg / cm ² is set. The polycarbonate is preliminarily dried at about 120 ° C. for about 5 hours before injection molding. Since the thermoplastic synthetic resin is made of polycarbonate, it has good moldability, has heat resistance, can withstand a temperature of, for example, 100 ° C. or more, and can be used to produce disposable chopsticks having high mechanical strength for use as chopsticks. it can.

When the thermoplastic synthetic resin is made of polystyrene, the temperature of the molten polystyrene injected from the nozzle of the molding machine is 190 to 260 as an injection molding condition.
° C, preferably about 190 ° C, the temperature of the first and second molds 21 and 22 is set at about 30 to 80 ° C, preferably about 55 ° C, and the injection pressure is about 400 to 1300.
kg / cm ² , preferably about 900 kg / cm ² . The polystyrene is preliminarily dried at about 80 ° C. for about 5 hours before injection molding. Since the thermoplastic synthetic resin is made of polystyrene, it has a good fluidity, easily flows into the first and second communication grooves 37 and 38, and the chopstick portions 2, 3
Can be reliably formed. Thereby, molding defects of the chopsticks manufactured by injection molding are reduced, and the productivity of the chopsticks is improved. In addition, since polystyrene is easily available and has high mechanical strength, disposable chopsticks that are inexpensive and have sufficient mechanical strength to be used as chopsticks can be manufactured. Furthermore, since the polystyrene has a small elongation, if a crack is formed in the connecting portion 6, the crack is easily propagated, and the connecting portion 6 can be easily divided.

When a polypropylene block copolymer is used as the polypropylene, an unfilled polycarbonate is used as the polycarbonate, and impact-resistant polystyrene is used as the polystyrene, the polypropylene block copolymer, the unfilled polycarbonate and the impact-resistant polystyrene are used. Table 1 shows the moldability, mechanical properties, thermal properties and chemical properties.

[0049]

[Table 1]

Here, regarding the mechanical properties, the tensile strength is A
Based on STM D 633 and ASTM D 651, the compressive strength is based on ASTM D 695, the flexural strength is based on ASTM D 790, and the notched Izod impact strength is based on ASTM D256. For thermal properties, the heat distortion temperature is based on ASTM D648. For chemical properties, the water absorption is as per ASTM D 57
Based on 0, the chemical resistance is based on ASTM D 543.

All of the above polypropylene, polycarbonate and polystyrene have good moldability and stable mechanical properties, thermal properties and chemical properties. Even when chopsticks are manufactured using any one of the above polypropylene, polycarbonate, and polystyrene, the mechanical, thermal, and chemical performances of the chopsticks are stable. Therefore, even if mass-produced disposable chopsticks, the quality of the product is stable. in this way,
Since the quality of the chopsticks made of any one of the above polypropylene, polycarbonate and polystyrene is stable as a product, (a) mechanical performance according to the shape of the connecting portion of each chopstick portion, for example, the chopsticks are placed at a certain height. (B) the thermal performance of each chopstick, such as the thermal performance of each chopstick at the operating temperature, and (c) the chemical performance of each chopstick, For example, even if the chopsticks are used to hold food such as pickled plums and pickled vegetables, many chopsticks with various performances such as the ability to achieve acid resistance and alkali resistance that each chopstick part does not cause chemical change even if it is used. Can be manufactured.

When imparting strong acid resistance and strong alkalinity excluding oxidizing acid to disposable chopsticks, polypropylene and polystyrene are preferably used. When the chopsticks are used temporarily in a strong alkali and in a strong acid, and when heat resistance is imparted to the chopsticks, polycarbonate is preferably used. When the chopsticks are washed and reused, any of polypropylene, polycarbonate and polystyrene may be used.

In still another embodiment of the present invention, the thermoplastic material may be a natural polymer resin such as an acetate resin and a natural polymer compound such as starch and mineral.
For example, it may be made of a biodegradable material containing calcium carbonate. Here, the acetate resin is a resin formed by acetylating a hydroxyl group of cellulose with ethyl acetate. When the material having thermoplasticity is composed of the biodegradable material, the temperature of the molten biodegradable material injected from the nozzle of the molding machine is 160 to 1 as an injection molding condition.
It is set to about 70 ° C. Since the biodegradable material has high water absorption, it is preliminarily dried at about 80 ° C. for about 5 hours before injection molding. The mechanical properties of the biodegradable material include a tensile strength of about 2.44 kg / mm ² , a bending strength of about 4.40 kg / mm ² , and an Izod impact strength of 3.
It is about 2 kg · cm / cm. As for the thermal properties of the biodegradable material, the thermal deformation temperature is about 61.9 ° C. The melt index is about 27.5. Therefore, the biodegradable material has good moldability and can produce disposable chopsticks having sufficient mechanical strength to be used as chopsticks. Natural polymer resins and natural polymer compounds are decomposed by soil microorganisms in soil, and minerals are originally contained in soil and are harmless even when scattered in soil. Therefore, even after use of the disposable chopsticks, even if they are disposed of as garbage, for example, landfilled, they can be disposed with less or no adverse effects on the environment, for example, soil pollution and water pollution. By burying disposable chopsticks made of a biodegradable material in soil as described above, decomposition of disposable chopsticks is promoted by chemical change of the soil itself, in addition to degradation by microorganisms. In the present embodiment, since the biodegradable material includes an acetate resin and starch, no harmful substances such as dioxin are generated even when incinerated. Further, the calorific value at the time of combustion is about half that of polypropylene or the like, and damage to the furnace wall of the incinerator can be prevented.

The biodegradable material may be mixed with fibers made of natural materials such as bamboo and wood. Here, bamboo fiber may be used as the fiber. Therefore, the chopsticks are reinforced by fibers and can have sufficient mechanical strength to be used as chopsticks. Moreover, since the fiber is made of bamboo fiber, it is decomposed in the soil by soil microorganisms. Therefore, disposable chopsticks can be disposed of with less or no adverse effects on the environment, such as soil and water pollution, even if they are disposed of as garbage, for example, landfilled. No material is generated.

In still another embodiment of the present invention, the thermoplastic material may be made of a natural polymer resin mainly composed of pulp. With this configuration, the disposable chopsticks made of the natural polymer resin are decomposed by soil microorganisms in the soil, and are discarded as garbage after use of the disposable chopsticks, for example, even if they are landfilled. And can be disposed of with less or no water pollution,
No harmful substances such as dioxin are generated by incineration.

In the above-described embodiment of the present invention, the material having thermoplasticity is made of a biodegradable material, but is not limited thereto, and may be made of a photodegradable material.

In still another embodiment of the present invention, the thermoplastic synthetic resin, which is a thermoplastic material, includes a powdery material made of a material having a melting point higher than that of the thermoplastic synthetic resin, for example, calcium carbonate powder. They may be mixed. At this time, the amount of the calcium carbonate powder mixed with the chopsticks is about 10 to 30% of the volume of the chopsticks. With such a configuration, even when the thermoplastic synthetic resin is melted, the granules can be dispersed in the molten thermoplastic synthetic resin without melting the granules. Therefore, the surface of the disposable chopstick made of the thermoplastic synthetic resin into which the powder and the granular material are mixed has irregularities due to the powder and the granular material, so that the disposable chopstick can be provided with an anti-slip effect. Here, when the amount of calcium carbonate mixed into the chopsticks is less than 10% of the volume of the chopsticks, the surface of the chopsticks cannot have sufficient unevenness, and the chopsticks cannot be provided with an anti-slip effect. When the amount of calcium carbonate mixed with the chopsticks exceeds 30% of the volume of the chopsticks, the bonding force between the molecules of the thermoplastic synthetic resin is weakened, and the strength of the chopsticks is reduced. In addition, by mixing the granular material with the thermoplastic synthetic resin, the amount of the thermoplastic synthetic resin necessary for molding is reduced by the amount of the mixed granular material for the disposable chopsticks of the same size where the granular material is not mixed. be able to. In addition, since calcium carbonate powder, which is a granular material, is a non-combustible substance, the amount of heat generated when incinerating disposable chopsticks composed of thermoplastic synthetic resin mixed with particulates is incinerated by disintegrating disposable chopsticks composed solely of thermoplastic synthetic resin. Can be made smaller than the amount of heat generated.

As still another embodiment of the present invention, an antibacterial agent such as zeolite powder may be mixed with the thermoplastic synthetic resin. With such a configuration, antibacterial properties can be imparted to the disposable chopsticks. Therefore, even if the disposable chopsticks are not used for a long period of time, the propagation of mold and germs can be prevented, which is hygienic. In addition, by using the disposable chopsticks in hospitals and nursing homes, the disposable chopsticks can be kept clean for inpatients and elderly people with reduced immunity.

In the embodiment of the present invention, one end 2a, 3a in the longitudinal direction of each disposable chopstick part 2, 3 is formed in a rectangular parallelepiped shape, and the portion excluding the one end 2a, 3a in the longitudinal direction is formed in a tapered substantially cylindrical shape. However, the present invention is not limited to this, and may be formed in other shapes such as a tapered substantially rectangular parallelepiped shape, a tapered substantially cylindrical shape, or a tapered triangular prism shape over the entire length of the chopstick portions 2 and 3 in the longitudinal direction. Is also good.

In the embodiment of the present invention, the first raised portion 44 and the second raised portion 49 are the first raised portions which are part of a spherical surface.
Although having a spherical raised surface 43 and a second spherical raised surface 48, in still another embodiment of the present invention, the first and second raised portions 44, 49 may be part of a conical surface or a pyramidal surface. It may have a part or the like. With this configuration, one end 2a of each of the chopstick portions 2 and 3 in the longitudinal direction is provided.
3a, recesses 50, 51, bottoms 52, 53 and gate pieces 5
The stress concentration ratio at the connecting portions 56 and 57 connecting to the gate pieces 54 and 55 increases, and the gate pieces 54 and 55 and the recesses 50 and 51
At the portions 56 and 57 with the bottoms 52 and 53.

As still another embodiment of the present invention, a spiral or annular groove may be formed at the other end 2b, 3b in the longitudinal direction of each of the chopstick portions 2, 3. With this configuration, the other end 2 in the longitudinal direction of each of the chopstick portions 2 and 3 is formed.
The grooves b and 3b are hardly slipped by the concave grooves, so that it is easy to hold an article such as food.

The disposable chopsticks 1 according to the embodiment of the present invention are used as chopsticks for eating, but as still another embodiment of the present invention, the disposable chopsticks 1 are formed in a longitudinal shape so as to be further used as chopsticks for cooking. You may do it.

[0063]

According to the first aspect of the present invention, the pair of disposable chopsticks is made of a thermoplastic material, and one end of each disposable chopstick in the longitudinal direction is defined in a facing surface facing each other. The region is integrally connected, and the predetermined region is
A region near the center between both ends in the width direction of each opposing surface perpendicular to the longitudinal direction of each disposable chopstick portion, and shifted from the centroid of each opposing surface in a direction away from the other longitudinal end of each disposable chopstick portion Therefore, the chopsticks can be easily divided at a part where the chopsticks are integrally connected, and the chopsticks can be separated substantially evenly. In addition, the length of the portion where the chopsticks are integrally connected in the direction along the longitudinal direction of each chopstick is sufficiently large relative to the thickness of the portion where the chopsticks are integrally connected, so that it can be manufactured, packed and transported. Depending on the vibration at the time,
It is possible to prevent a part where the disposable chopstick parts are integrally connected from breaking. Furthermore, since the portion where each disposable chopstick part is continuously connected is selected as a predetermined area on each of the opposing surfaces, even if mass production of disposable chopsticks is performed, any part of the disposable disposable chopsticks is continuously connected to any disposable chopsticks. Is formed in a predetermined area, as in extrusion molding, the area where the connecting portion of each chopstick is formed is different for each product, and the connecting strength of the connecting portion is different for each product. No trouble occurs.

According to the second aspect of the present invention, the thermoplastic material is made of one of polypropylene, polycarbonate and polystyrene.
Disposable chopsticks having good moldability, sufficient mechanical strength for use as chopsticks, and stable product quality can be manufactured.

According to the third aspect of the present invention, the thermoplastic material is composed of a biodegradable material containing at least a natural polymer resin, a natural polymer compound and a mineral. Natural polymer compounds are decomposed by soil microorganisms in soil, and minerals are originally contained in soil and are harmless even when scattered in soil. Therefore, even after use of the disposable chopsticks, even if they are disposed of as garbage, for example, landfilled, they can be disposed with less or no adverse effects on the environment, for example, soil pollution and water pollution.

According to the fourth aspect of the present invention, since a material having a higher melting point than the material having thermoplasticity is mixed with the material having thermoplasticity, the material having thermoplasticity is mixed. Even when the material is melted, the granules can be dispersed in the molten thermoplastic material without melting the granules. Therefore, the surface of the disposable chopstick made of a thermoplastic material mixed with the powder and granules has irregularities due to the powder and granules, and the disposable chopstick can be provided with an anti-slip effect. In addition, by mixing the granules with the thermoplastic material, the amount of the thermoplastic material required for molding is determined by the mixing amount of the granules for the disposable chopsticks of the same dimensions where the granules are not mixed. Can be reduced by minutes.

According to the fifth aspect of the present invention, an antibacterial agent is mixed with the thermoplastic material, so that antibacterial properties can be imparted to the disposable chopsticks. Therefore, even if the disposable chopsticks are not used for a long period of time, the propagation of mold and germs can be prevented, which is hygienic.

According to the sixth aspect of the present invention, the first mold is moved in a direction away from the second mold while the chopstick is engaged with the inner surface forming the first groove, and the chopstick is moved. Since one of the chopstick portions of the disposable chopsticks is engaged with the inner surface of the first mold forming the first groove, one of the disposable chopstick portions of the disposable chopsticks is engaged with the other of the disposable chopstick portions. 2nd mold second
The first mold is inserted into the second mold while being engaged with the inner surface forming the concave groove.
By moving in the direction away from the mold, each chopstick part is cut off at a continuous part, or each chopstick part is engaged with the second groove and it takes time to remove the chopsticks from the second mold, etc. Thus, the disposable chopsticks can be reliably pushed out of the first mold and separated.

According to the seventh aspect of the present invention, the region surrounded by the first end face at one end in the longitudinal direction of the inner surface extending in the longitudinal direction of each first concave groove of the first mold is provided with: One raised portion is formed, and a second raised portion is formed in a region surrounded by a second end surface of one longitudinal end of an inner surface extending in a longitudinal direction of each second concave groove of the second mold. Since injection molding is performed using the first and second molds, a concave portion is formed at each longitudinal end of each of the chopstick portions of the chopsticks corresponding to the first and second raised portions. Gate pieces formed by the gates are integrally connected to the bottom. Therefore, each chopstick portion is separated from each gate piece by its own weight when the chopstick portion is extruded and separated from the first mold, so that a step of manually separating each chopstick portion from each gate piece can be omitted, Productivity can be improved. Further, since each gate piece is broken at a base end portion connected to the bottom of each recess of each gate piece, the broken portion of each gate piece is formed by the first end face of each first groove and the second recess. The broken portion does not protrude outside from an imaginary plane including the end surface of each longitudinal end of each chopstick portion corresponding to the second end surface of the groove, and the broken portion is inconspicuous.

[Brief description of the drawings]

FIG. 1 is a plan view showing a simplified configuration of a disposable chopstick 1 according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a section 2 of FIG. 1;

FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 2;

FIG. 5 is a diagram for explaining a method of manufacturing the chopsticks 1 according to one embodiment of the present invention.

6 is a cross-sectional view showing a state where each of the chopstick portions 2, 3 is engaged with a first concave groove 23. FIG.

FIG. 7 is an enlarged plan view showing a part of a second mold 22;

FIG. 8 is an enlarged cross-sectional view showing the vicinity of one longitudinal end of first and second grooves 23 and 24 in a state where the first mold 21 and the second mold 22 are clamped.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disposable chopsticks 2, 3 Disposable chopsticks parts 4, 5 Opposite surface 21 First die 22 Second die 23 First concave groove 24 Second concave groove 25 Gate 26 Runner 27 Sprue 41, 46 Inner surface 44 First raised portion 49 Second Raised part

Claims (7)

[Claims] 1. A pair of disposable chopsticks made of a thermoplastic material, and one end of each disposable chopstick in the longitudinal direction is integrally connected to each other in a predetermined area in each opposing surface. The predetermined area is near the center between the widthwise ends of each of the chopstick portions on each opposing surface, which is perpendicular to the longitudinal direction, and from the other end in the longitudinal direction of each of the chopstick portions than the centroid of each opposing surface. Disposable chopsticks characterized by being selected at a position shifted in the direction of separation. 2. The disposable chopstick according to claim 1, wherein the material having thermoplasticity is made of any one of polypropylene, polycarbonate and polystyrene. 3. The disposable chopstick according to claim 1, wherein the thermoplastic material comprises a biodegradable material containing at least a natural polymer resin, a natural polymer compound and a mineral. 4. The material according to claim 1, wherein a powdery material made of a material having a higher melting point than the material having thermoplasticity is mixed with the material having thermoplasticity. Disposable chopsticks. 5. The disposable chopstick according to claim 1, wherein an antibacterial agent is mixed with the thermoplastic material. 6. A first pair of first recesses extending substantially in parallel and communicating with each other at one end in the longitudinal direction.
A pair of molds and a pair of second grooves extending substantially parallel to each of the first grooves and communicating with each other at one end in the longitudinal direction are formed adjacent to each other. A first mold is provided, in which a runner for introducing a molten thermoplastic material to a gate communicating with the gate at one end in the longitudinal direction and a sprue for introducing a molten thermoplastic material to the runner are formed. After the first mold and the second mold are clamped in a state where the grooves and the second grooves are opposed to each other, the molten thermoplastic material is discharged from the sprue to the first mold via the runner and the gate.
And injecting into the second groove, filling the first and second grooves with the molten thermoplastic material, after curing the molten thermoplastic material filled in the first and second grooves, The first mold and the second mold are released from each other, and have a pair of disposable chopsticks made of a thermoplastic material. The first mold is moved in a direction away from the second mold in a state where the chopsticks integrally connected in the predetermined area are engaged with the inner surface forming the first groove, and the chopsticks are moved from the first mold. A method for producing disposable chopsticks, which is extruded and detached. 7. A region surrounded by a first end surface of one end in a longitudinal direction of an inner surface extending in a longitudinal direction of each first concave groove of the first mold, a longitudinal direction from an imaginary plane including the first end surface. A first raised portion protruding toward the other end is formed, and a region surrounded by a second end surface at one longitudinal end of an inner surface extending in a longitudinal direction of each second concave groove of the second mold includes: 7. The method according to claim 6, further comprising forming a second raised portion projecting from the virtual plane including the second end surface toward the other end in the longitudinal direction, and performing injection molding using the first and second molds. Production method of disposable chopsticks.