JP2833481B2 - Buckling resistant plastic bottle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buckling-resistant plastic bottle and, more particularly, to a buckling-resistant plastic bottle which exhibits excellent buckling resistance against an axial load and is capable of hot-filling the contents. The present invention relates to a plastic bottle that can be used for packing.

[0002]

2. Description of the Related Art Plastic hollow containers are widely used as packaging containers for various liquids because of their excellent lightness and impact resistance. In particular, polyethylene terephthalate (PET) is stretch blow-molded. The hollow container consists of transparency, gas barrier properties, light weight, impact resistance,
It has a combination of appropriate rigidity and the like, and is widely used as a packaging container for containing liquid contents.

In this blow-molded container, efforts have been made to reduce the weight per unit area in order to reduce the material cost of the container or to reduce the weight of the container. The problem is that bowing occurs.

[0004]

The buckling of plastic bottles is mainly at the shoulder, which is located between the neck and the torso, and the neck is thickened for fastening with the lid. On the other hand, the body is highly oriented and stretched, the perimeter is large and the axial load is dispersed, while the shoulder is thinned by stretching in consideration of the appearance or strength of the container. It is recognized that the perimeter is small and the axial load per unit length is large.

[0005] The buckling of a plastic bottle naturally occurs when the weight of the container is reduced, but it is particularly likely to occur in a rectangular container, particularly a container having a rectangular cross section. That is, in the case of a rectangular container, the volume of the carton case for accommodating them is reduced, the accommodation in the refrigerator can be made compact, and the advantage that the grip by hand is easier than that of a circular container is provided. Since the shape of the shoulder portion is not axisymmetric, a portion where stress concentrates is formed, and such buckling easily occurs.

Accordingly, an object of the present invention is to provide a plastic bottle in which the tendency of buckling at the shoulder is eliminated, particularly a bottle having a rectangular cross section. Another object of the present invention is to
The shoulder is thinned, and even if the weight of the container is reduced, excellent buckling strength is still obtained, and even when the container is hot-filled with contents, asymmetry or irregular deformation at the shoulder is effectively achieved. To provide a plastic bottle that is prevented.

[0007]

According to the present invention, there is provided a plastic bottle formed by blow molding or stretch blow molding of plastic and having a neck, a frustum-shaped shoulder, a cylindrical body, and a closed bottom. The frustum-shaped shoulder has a plurality of radial peaks extending from the base of the neck to the outer periphery of the shoulder, and a plurality of peaks located inward and adjacent to the lower side of the peak and at a smaller interval than the outer periphery of the shoulder. A vertex provided so as to be located substantially in the middle of the line (the vertex in the present specification means a point where surfaces intersect in a polyhedron) and a vertex arranged almost in the middle between adjacent mountain lines, and A divergent concave body consisting of a radially long valley line connecting a vertex and a pair of short valley lines connecting the vertex and the outer peripheral edge of the mountain line is arranged continuously in the circumferential direction. Buckling resistant plastic body Le is provided.

In the present invention, the polygon formed when the truncated frustum-shaped shoulder is cut along the horizontal plane at the radial valley line is represented by the following equation (1) α <180-360 / n ‥‥ (1) It is desirable to have, on average, a vertex angle (α) that satisfies
In particular, equation (2) α = k (180-360 / n) ‥‥ (2) where, in the equation, the number of angles of the n polygon, and k is 0.95 to 0.8
5, which most preferably is a number from 0.94 to 0.90. The angle (.beta.1) of the peak line with respect to the horizontal plane is between 45 and 52.degree., Especially 47-49.degree., While the angle (.beta.2) of the valley line with respect to the horizontal plane is between 47 and 55.degree., Especially between 49 and 52.degree. It is good.

Further, the number of connected concave concave bodies (n)
Although it depends on the size of the container, it is generally preferably in the range of 10 to 16, particularly preferably 12 to 14.
In addition, the valley between adjacent mountain lines may be located on the curvature plane, or the valley between adjacent mountain lines may be located on the inverted trapezoidal surface.

The bottle of the present invention is particularly useful when the cylindrical body has a rectangular cross section with a horizontal cross section, in which case the divergent concave bodies are connected in a substantially equal area. It is good to be.

[0011]

The plastic bottle of the present invention is formed by plastic blow molding or stretch blow molding and has a neck, a frustum-shaped shoulder, a cylindrical body, and a closed bottom. It is a remarkable feature that a frustum-shaped shoulder in which a divergent concave body is connected in the circumferential direction is formed instead of the shoulder.

In FIG. 1 (top view) and FIG. 2 (side view) showing the connecting and arranging structure of the divergent concave body in the present invention, the frustum-shaped shoulder 1 extends from the base of the neck 2 to the outer periphery 3 of the shoulder. The plurality of radially extending mountain lines 4a and 4b are positioned below the mountain lines 4a and 4b, at an interval smaller than the outer circumference of the shoulder, and substantially in the middle of the adjacent mountain lines. The provided vertex 5 and the adjacent mountain line 4
A pair 7 of a long radial valley line 6 which is disposed almost in the middle between the a and 4b and connects the base of the neck and the apex 5, and a short valley line 6 which connects the apex 5 and the outer peripheral edge of the apex lines 4a and 4b. , 8 are formed. That is, the concave body has a surface defined by lines 4a, 6 and 7, a surface defined by lines 6, 4b and 8, lines 7, 8
And 3 are the three surfaces defined by the above. A large number of the divergent unit concave body structures are connected in the circumferential direction, and twelve in the specific example shown in the figure.

According to the present invention, the shoulder has a contiguous arrangement of the flared concave body 9 so that the buckling resistance is remarkably higher than that of a conventional truncated pyramid-shaped shoulder. Improvements are brought. FIG. 3 shows a container (A) having the above-mentioned divergent concave body articulated arrangement of FIG. 1 and a conventional shoulder (only the flat surface defined by lines 4a, 4b and 3 in FIG. 7 is a graph in which the relationship between the axial load and the strain is plotted for the container (B) having (a). In FIG. 3, the shoulder-shaped first peak seen at the rise of the load application indicates the buckling occurrence point. According to the results of FIG. 3, buckling is observed at about 30 kgf in the conventional container (B), whereas the buckling strength of the container (A) of the present invention is close to the breaking strength of the container. The surprising fact that it is improved to about 44 kgf becomes clear.

In FIGS. 4 and 5 for explaining the principle of buckling, the axial load f0 applied to the shoulder 1 is divided into a component force f1 parallel to the shoulder surface and a component force perpendicular to the shoulder surface. And at the connection between the shoulder and the upper part of the torso, the above-mentioned component force f1 is a component force f1a for expanding the container wall outward and a component force f1b along the body container wall. And divided into It is recognized that the above-mentioned component force f1a and component force f2 act on the shoulder portion of the conventional container, which causes buckling near the connection portion. In particular, in the case of a container having a rectangular body section, the inclination angle of the shoulder is different between the long side and the short side of the body.
1a is different, which is why buckling is likely to occur on the short side of the container.

On the other hand, in the container of the present invention, the connecting structure of the divergent concave body is formed at the shoulder, and the vertex (5) of the concave body and the small triangle are located at positions where the shoulder is likely to buckle. Since the surfaces (the surfaces defined by the lines 7, 8 and 3) are arranged, the reinforcing structure is strengthened against buckling. In the present invention, the above-mentioned divergent concave body has the above-mentioned component force. It is considered that the structure that withstands f2 and f1a and easily disperses them increases the buckling resistance.

In the container of the present invention, the polygon formed when the truncated frustum-shaped shoulder is cut along the horizontal plane at the radial valley line 6 is represented by the formula α <180-360 / n, where n is the corner of the polygon. Apex angle (α) that satisfies
On average. In a conventional truncated pyramid-shaped shoulder, the average apex angle (α) of the polygon is equal to the right side of the above equation. However, in the present invention, the apex angle (α) ) Can be made smaller than in the conventional case, thereby improving the buckling resistance. When the apex angle (α) of the polygon is given by the formula α = k (180-360 / n), k = 0.95 to 0.85, especially 0.94 to
It is preferable that the number is 0.90 in terms of strength and formability. If k exceeds the above range, the buckling resistance becomes unsatisfactory. Is not preferable, and the basis weight of the resin increases.

The angle (β1) formed by the mountain line with respect to the horizontal plane is 45 to 52 °, particularly 47 to 49 °, and the angle (β2) formed by the valley line with respect to the horizontal plane is larger than the angle (β1). The large size is one of the features of the present invention, and is generally in the range of 47 to 55 °, particularly 49 to 52 °. When the valley line angle (β2) is smaller than the above range, the buckling resistance tends to be inferior.

The number of connected (n) of the divergent concave body is preferably in the range of 10 to 16, particularly 12 to 14 in terms of buckling resistance and shapeability.

The valley between adjacent peak lines can be located on the curvature surface, in which case the curvature radius (R) of the curvature surface is
In general, it is advantageous in the range of 40 to 100 mm, particularly 70 to 90 mm, in terms of strength and shapeability.

Further, the valley between adjacent mountain lines can be located on the inverted trapezoidal surface. In this case, the width dimension (X) of the valley is about 2 to 6 mm from the same viewpoint.

The present invention is particularly advantageously applicable to heat-resistant containers whose tubular body is rectangular in horizontal cross section with rounded corners, in which case the divergent concave bodies have a substantially equal area. It is preferable that the connection is made in order to further improve the buckling strength.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A plastic bottle according to the present invention will be described with reference to the drawings.

FIG. 6 is a front view of one embodiment of the plastic bottle of the present invention, and FIG. 7 is a right side view of the bottle of FIG. 6 (the left side view is the same as FIG. 7). 8 is a top view (plan view) of the bottle of FIG. 6, FIG. 9 is a bottom view of the bottle of FIG. 6, FIG. 10 is a sectional view taken along AA (side sectional view) of FIG.
FIG. 11 is a sectional view taken along line BB (horizontal sectional view) in FIG. 6, and FIG. 12 is a sectional view taken along line CC in FIG.

As shown in FIGS. 6 to 12, the plastic bottle of the present invention comprises a neck portion 2, a shoulder portion 1, a cylindrical body portion 10 and a closed bottom portion 11, and the shoulder portion 1 is provided with the components shown in FIGS. 12, the divergent concave body unit 9 described in detail in 2,
They are arranged continuously in the circumferential direction.

The cylindrical body 10 includes an upper body 12 and a lower body 13.
The upper and lower parts are divided into upper and lower parts via reinforcing ribs (concave ribs) 14, each of which comprises a long side part 15, a short side part 16, and a corner 17 which is rounded.

The long side 15 and the short side 16 of the upper body 12 and the lower body 13 are provided with a reduced-pressure absorbing surface (panel) 18 for absorbing reduced-pressure shrinkage due to cooling during hot filling. In order to prevent the pressure-deformation deformation from propagating to other parts, the pressure-deformation deformation is provided above and below the pressure-reduction absorbing surface 18 of the lower body portion 13 and below the pressure-reduction absorption surface 18 of the long side portion 15 of the upper body portion 12, respectively. A concave bead 19 is provided.

The upper part of the upper torso part 12 has a connection part 2 with the shoulder part 1.
In the lower part of the lower body 13, there is an inverted frustum-shaped connection 21 with the bottom 11.

As best shown in FIG. 8, the shoulder 1 of this embodiment has a larger diameter in the long side direction of the torso than in the short side direction of the torso. Short side 16 of
It is difficult to connect directly to the periphery of the shoulder 1, so that they are connected via a truncated pyramid-shaped connecting portion 20 as a whole.

More specifically, in the specific example shown in the drawings, of the twelve divergent concave body structures, two concave bodies 9 are provided on each long side 15 of the body, and two concave bodies are provided on each short side 16 of the body. One concave body corresponds to each of the concave bodies 9 and each of the corner portions 17, and in the connecting portion 20, an axial load applied to the shoulder portion 1 is smoothly transmitted to the body portion 10. I have. That is,
The torso long side portion 15 is composed of two top sides 2 on the same plane.
2, a top 23 of the triangle defined by 2 and 22 (only the top 23 is bent inwardly at the very tip) and an inverted triangular surface 24 which is bent inward through the top side 22 and is adjacent to the top 23. Are connected to the concave body 9 while the body short side 16
Are bent inward through a top 27 and a top 26 of a triangle defined by two vertices 25 and 25 and a fold line 26, and two concave bodies are formed through an adjacent inverted triangular surface 28. 9, and the corner portion 17 is connected to the concave body 9 via a quadrilateral surface 29.

In FIG. 11 showing a horizontal section of the shoulder 1,
The shoulder section 4a (or 4b) (FIG. 1)
2), a vertex 30 and an inwardly concave surface 31 exist. A radial valley line 6 exists at the center of the concave surface 31. In FIG. 1, a mountain line 4 is shown on the horizontal and vertical lines.
Although a is located, the radial valley line 6 may be located.

In FIG. 13 showing the shoulder 1 in an enlarged manner and explaining the relationship of the apex angle (α), A shows the shoulder of the container of the present invention, and B shows the shoulder of the conventional container. Therefore, while the apex angle (α) of the conventional container is 150 degrees on average,
It is apparent that the apex angle (α) of the container of the present invention is lower than 150 degrees on average, and is provided within the range satisfying the expression (2).

FIG. 14 shows an example of the horizontal sectional shape of the shoulder 1.
, The concave surface 31 of the shoulder portion 1 is a curvature surface, and the curvature radius (R) of the curvature surface is generally 40 to 100 mm,
In particular, it is in the range of 70 to 90 mm. It should be understood that the radius of curvature (R) of the curvature surface can vary within the same shoulder.

In FIG. 15 showing another example of the horizontal cross-sectional shape of the shoulder 1, the concave surface 31 of the shoulder 1 is an inverted trapezoidal surface, and the width dimension (X) of the valley is 2 to 6 mm. ing.

In FIG. 16 for explaining the arrangement of the divergent concave body unit 9 with respect to the shoulder portion 1, PL indicates a parting line of a blow molding die, and each concave body unit 9 has a long diameter surface and a short diameter surface. They are arranged plane-symmetrically and axially symmetrically with respect to the central axis. The shape of the shoulder portion 1, but is as already pointed out taking larger than the diameter D ₁ of the cylinder long side to a radial D ₂ of the body portion short side direction, in the present invention, it flared concave body units 9 are connected in such a relationship that their bottom surface areas are substantially equal. That is, for the concave unit 9a having the largest radius, the taper angle is set to 28.5 degrees, which is the smallest. For the concave unit 9c having the smallest radius, the taper angle is set to 31.5 degrees, which is the largest. For the intermediate concave body unit 9b, the taper angle is set to the intermediate 30 degrees, the areas are made almost equal, and the balance of strength is maintained.

In FIG. 17, which shows the peak line and the valley line of each concave unit, the longest peak line 4a1 in the concave unit 9a, the peak line 4b1 common to the concave unit 9a and the concave unit 9b, and the concave unit The peak line 4a2 common to the unit 9b and the concave unit 9c, the shortest peak line 4b2 in the concave unit 9, the valley line 6a of the concave unit 9a, the valley line 6b of the concave unit 9b, and the valley line of the concave unit 9c The inclination angle of the horizontal line 6c with respect to the horizontal plane is shown in Tables 1 and 2 in the embodiment of FIG.
It was as follows.

[0036]

[Table 1]

[0037]

[Table 2]

On the other hand, the conventional bottle shown in FIG. 3B has an inclination angle corresponding to the inclination angle of the mountain line shown in Table 1 above.

The bottle of the present invention is used for hot filling of contents and sealing as it is. In order to seal the contents, the bottle neck 2 is provided with a screw 34 for opening and closing the cap, a step 35 for fastening the pill fur proof cap, and the like, and further supports the bottle in the manufacturing process and the filling process. A support ring 36 is provided. Also,
The bottom portion 11 has a dome shape in which the central portion 37 is higher than the ground surface 38, and the seating on the support surface is improved.

The bottle of the present invention is manufactured by blow molding or stretch blow molding of a plastic parison or preform. That is, the extruded molten plastic parison is blow-molded in a blow mold, or an amorphous plastic preform is manufactured by injection molding, and the preform is stretch blow-molded in a blow mold.

As the plastic for the bottle, any thermoplastic resin that can be molded can be used. Examples of such resins include thermoplastic polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate; polycarbonates; acryl-butadiene-styrene copolymer (ABS resin); polyacetal resins; Nylons such as nylon; acrylic resins such as polymethyl methacrylate; isotactic polypropylene; low-, medium- or high-density polyethylene, ethylene-propylene copolymer, ethylene-butene-1 Examples thereof include a polymer and a styrene-butadiene thermoplastic elastomer.

For the purpose of increasing the strength while reducing the basis weight of the bottle, a thermoplastic polyester is preferred. Examples of the thermoplastic polyester include thermoplastic polyesters mainly composed of ethylene terephthalate units, for example, polyethylene terephthalate (PET), and a small amount of other glycols such as hexahydroxyrylene glycol as a glycol component, or isophthalic acid as a dibasic acid component. So-called modified PET containing a small amount of other dibasic acid components such as hexahydroterephthalic acid and the like is used. These polyesters can be used alone or in the form of a blend with other resins such as small amounts of nylons, polycarbonates or polyarylates, as long as the nature thereof is not impaired.

The intrinsic viscosity (η) of the thermoplastic polyester used may be a bottle forming grade, and is 0.65 dl /
g, especially 0.70 to 0.90 dl / g, and the content of diethylene glycol unit is 1.60.
Those within the range of not more than 1.50% by weight, especially not more than 1.50% by weight are preferably used.

The bottomed preform used for the stretch blow molding can be prepared by any method known per se, for example, injection molding,
It is manufactured by a pipe extrusion method or the like. In the former method, molten polyester is injected, and a preform with a bottom and a neck corresponding to the final container is manufactured in an amorphous state. In the latter method, an extruded amorphous pipe is cut, a mouth and a neck are formed at one end by compression molding, and the other end is closed to form a bottomed preform. In general, it is preferable to manufacture by an injection molding method. Injection conditions and the like are not particularly limited, but generally, a bottomed preform can be molded at an injection temperature of 260 to 300 ° C. and an injection pressure of 30 to 60 kg / cm ² .

The preform thus obtained has heat resistance,
In order to provide rigidity, in the preform stage, the mouth and neck having a screwing portion, a fitting portion, a support ring, etc. may be crystallized and whitened by heat treatment. After the molding is completed, the mouth and neck portion of the unstretched portion may be crystallized and whitened.

The preform to be stretch blow-molded is preheated to a stretching temperature, generally between 100 and 130,
Next, it is biaxially stretched. In a hollow mold, a thermoplastic polyester preform preheated to the above temperature is mounted, and the preform is expanded and stretched in the circumferential direction,
Pull and stretch in the axial direction.

The stretching ratio in the final container is suitably from 5 to 14 times, particularly from 7 to 12 times, in area ratio, while the stretching ratio in the axial direction is from 2 to 3.5 times, especially from 2.5 to 3 times. The draw ratio in the circumferential direction is preferably 2 to 5 times, and more preferably 3 to 4 times. Further, the molded container can be heat-set in order to impart heat resistance to the container.

[0048]

According to the present invention, instead of the conventional frustoconical or truncated pyramid shoulder, a frustoconical shoulder is formed by arranging divergent concave bodies connected in the circumferential direction. The occurrence of buckling in the portion was significantly suppressed, and the buckling resistance was significantly increased. In addition, this makes it possible to reduce the basis weight of the container, thereby reducing the material cost of the container and the weight of the container. In addition, even when used as a hot-fill container, irregular deformation (dent deformation) and the like at the shoulder are prevented,
Product value can be increased.

[Brief description of the drawings]

FIG. 1 is a top view for explaining a shoulder structure of a buckling-resistant plastic bottle of the present invention.

FIG. 2 is a front view for explaining a structure of a shoulder portion of the buckling-resistant plastic bottle of the present invention.

FIG. 3 is a graph plotting the relationship between the axial load and the strain for a container (A) having a shoulder with an articulated arrangement of concave bodies and a container (B) having a conventional shoulder according to the present invention.

FIG. 4 is an explanatory diagram for explaining the principle of occurrence of buckling at a shoulder.

FIG. 5 is another explanatory view for explaining the principle of occurrence of buckling at the shoulder.

FIG. 6 is a front view of an embodiment of the buckling-resistant plastic bottle of the present invention.

FIG. 7 is a right side view showing the bottle of FIG. 6 rotated by 90 °.

FIG. 8 is a top view of the bottle of FIG. 6;

FIG. 9 is a bottom view of the bottle of FIG. 6;

FIG. 10 is a sectional view taken along the line AA in FIG. 6;

FIG. 11 is a schematic sectional view taken along line BB in FIG. 6;

FIG. 12 is a sectional view taken along line CC in FIG. 6;

FIG. 13 is an explanatory diagram showing an enlarged cross section taken along line BB in FIG. 6 and showing a difference in apex angle from the conventional one.

FIG. 14 is an explanatory diagram showing an example of a concave shape of a shoulder portion of the present invention.

FIG. 15 is an explanatory view showing another example of the concave shape of the shoulder portion of the present invention.

FIG. 16 is an explanatory diagram showing an example of an arrangement of concave body units in a shoulder according to the present invention.

FIG. 17 is an explanatory diagram showing the arrangement of peak lines and valley lines in the arrangement of concave body units in FIG. 16;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shoulder part 2 Neck part 3 Shoulder outer periphery 4a and 4b Crest line 5 Vertex 6 Radial valley line 7 and 8 Short valley line 9 End-expanding concave body 10 Body 12 Upper body 13 Lower body 14 Concave bead 15 Body long side 16 Body short side 17 Body corner 18 Decompression absorbing surface 19 Deformation prevention bead 20 Upper body connection 21 Lower body connection 30 Shoulder top 31 Concave shoulder

Claims (9)

(57) [Claims] 1. A plastic bottle formed by blow molding or stretch blow molding of plastic and having a neck, a frustum-shaped shoulder, a cylindrical body, and a closed bottom, wherein the frustum-shaped shoulder is attached to a base of a neck. And a plurality of radial peak lines extending from the shoulder line to the outer periphery of the shoulder portion, and provided so as to be located below the peak line, at an interval smaller than the outer periphery of the shoulder portion, and substantially in the middle between adjacent peak lines. A pair of a short valley line that is disposed approximately at the center of the adjacent peak line and that connects the root of the neck and the vertex, and a short valley line that connects the vertex and the outer peripheral edge of the peak line. A buckling-resistant plastic bottle characterized in that a divergent concave body consisting of 2. A polygon formed when the truncated frustum-shaped shoulder is cut along a horizontal plane at a radial valley line portion, where α <180-360 / n, where n is the number of polygons. 2. The buckling-resistant plastic bottle according to claim 1, having a satisfactory apex angle (α) on average. 3. A polygon formed when the truncated frustum-shaped shoulder is cut along a horizontal plane at a radial valley line is represented by the following equation: α = k (180-360 / n) Yes, k is 0.95 to 0.85
The buckling-resistant plastic bottle according to claim 1, having an average apex angle (α) satisfying the following expression. 4. The connecting number (n) of the divergent concave body is 10
The buckling-resistant plastic bottle according to any one of claims 1 to 3, wherein 5. The buckling-resistant plastic bottle according to claim 1, wherein valleys between adjacent mountain lines are located on the curvature plane. 6. The buckling-resistant plastic bottle according to claim 1, wherein valleys between adjacent mountain lines are located on an inverted trapezoidal surface. 7. An anti-shock device according to claim 1, wherein the angle (β) of the mountain line with respect to the horizontal plane is 45 to 52 °, and the angle (β) of the valley line with the horizontal plane is 47 to 55 °. Buckling plastic bottle. 8. The buckling-resistant plastic bottle according to claim 1, wherein the tubular body has a rectangular cross section with a horizontal cross section. 9. The buckling-resistant plastic bottle according to claim 7, wherein the divergent concave bodies are connected so as to have substantially the same area.