JP3064280B1 - Packaging buffer and packaging structure - Google Patents

Abstract

An object of the present invention is to provide a cushioning material for packaging which has an excellent cushioning function, is excellent in workability when storing articles, and does not generate harmful gas even when incinerated after use. A packaging cushion (50) is constituted by using a pair of cardboard members (5). The cardboard member (5) has a concave surface (5
1) The concave surface (51) is constituted by a bottom portion (511) and a sloped side portion (512).
It is curved to 1). Corrugated components
In (5), the bottoms (511) are adhered to each other so that the concave surface (51) faces outward, and integrated. A cutout (52) for fixing the article in the accommodation space is formed in the cardboard member (5) on the article accommodation side of the packaging cushion (50). Notches forming the locking pieces (53) are formed at required positions on the peripheral edge of the cardboard member (5) on the article storage side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a cushioning member and a packaging structure for use in packaging articles, and more particularly has an excellent cushioning function of absorbing external impact, and, the cushioning member is excellent in workability can accommodate easily article with minimal effort and a packaging structure.

[0002]

2. Description of the Related Art When transporting articles that are vulnerable to impact, sufficient consideration must be given to the packaging of the articles. As a packaging form that does not give an impact to an article, a method of filling a void portion formed between the article and the packaging container with various types of cushioning materials for packaging is generally used. For example, a method of stuffing a piece of paper such as newspaper into a gap formed in a packaging container, a method of packing a large number of air cushions for packaging having independent air chambers into a gap formed in a packaging container, a corrugated cardboard material By forming a storage mold frame that can accommodate the articles without gaps by folding the formed partition plate, a method of storing and packaging the articles in the storage mold frame, the articles are formed by using a foamed plastic such as expanded polystyrene. A method of forming a housing mold body that can be housed without gaps, and housing and packaging the article in the housing mold body, and the like.

[0003]

However, the above-mentioned conventional method has the following problems. The method of using a piece of paper such as newsprint requires a work of rolling a plurality of newsprints one by one and pushing them into a gap portion, which requires a great deal of labor and labor. Also, a cushioning material for packaging using newsprint has a weak strength against external impacts due to the nature of the material, and is not suitable as a cushioning material for precision instruments and the like, which is particularly vulnerable to shocks.

The method of using a large number of air cushions for packaging is excellent in cushioning property for absorbing external impacts. However, as in the case of using a piece of paper such as newspaper, a large number of cushioning materials are used to form a gap. Workability was poor because it was necessary to fill in the parts.

[0005] The method using the storage mold frame constituted by the partition plate using the corrugated cardboard material is excellent in workability when accommodating articles, but the storage mold frame itself simply bends the corrugated cardboard material. Since it was formed only by impact, the impact from the outside was easily transmitted directly to the article, and the impact absorption was poor.

[0006] The method of protecting articles by using a housing frame formed of foamed plastic is excellent in shock absorption, but after unpacking, there is no choice but to treat it except incineration. Environmentally unfavorable such as soot formation.

(Object of the Invention) Accordingly, an object of the present invention is to provide an excellent shock absorbing function for absorbing an external impact, and to provide excellent workability in which articles can be easily stored without trouble. and to provide a cushioning body and packaging structures. Another object of the present invention is to provide a cushioning material for packaging and packaging structures harmful gases be incinerated is not generated after use.

[0008]

Means of the present invention taken to achieve the above object are as follows. In the first invention, the bottom is formed around the bottom and the slope is formed.
Corrugated board having a concave surface constituted by
Comprising a two Le made member, two members made stepped balls, is provided with a combination like concave side in contact with respective bottoms out side is outwardly respectively, the corrugated board member,
Space by the concave surface is formed, also has a flexibility toward the bottom of at least the side or sides, the upper
The concave surface is a flexible rubber that expands when air is supplied.
Surface pressure when the pressing body made of sheet
Therefore, it is a packaging cushion characterized by being formed .

In the second invention, a pair of the first inventions
Consists cushioning body according to, the cushion is combined so as to face the concave surface side, characterized in that the housing space of the article is formed by the concave, the cushioning member.

In the third invention, the corrugated cardboard member is
The packaging cushion according to the first or second invention, characterized in that a means for fixing the article is provided on the side .

According to a fourth aspect of the present invention, there is provided the packaging cushion according to the third aspect, wherein the means for fixing the article is constituted by a notch (52). .

[0012] In the fifth invention, the first, characterized in that it comprises a packaging box for packaging the cushioning body according to 2, 3 or 4 of the present invention is a packaging structure.

Examples of the shape of the "packing buffer" according to the present invention include a container having a concave surface and a thin plate attached to the outer bottom side of the container.
When the packaging cushion is used alone, the article is fixed on the concave side, and the packaging cushion to which the article is secured is further packaged in a packaging box or the like to protect the article. When two or more packaging cushions are used in combination, they are combined so that the concave sides face each other, and the article is accommodated in the accommodation space constituted by the plurality of concave faces.

The "articles" to be packaged include, for example, information terminal equipment such as a PDA (Personal Digital Assistant), a notebook computer, precision equipment such as a mobile phone, a wristwatch or an IC substrate, video tape, and audio. Examples include tapes, music CDs, computer software CD-ROMs, data recording media such as FDs, and other broken items such as tableware.

(Operation) The packaging cushion according to the present invention comprises:Shaped around the bottom and around the bottom
Formed by a concave side with a sloped side
A corrugated cardboard member comprising two corrugated cardboard members having surfaces
The two pieces of wood have their bottom sides touching each other and the concave side
Are installed so that they face outward.
In the ball member, a space is formed by the concave surface,
Also flexible at least from the side or from the side to the bottom
have.Also,SecondAccording to the inventionPackaging cushion
IsA pair of packaging cushions according to the first invention,
The buffer isConcave sideToCombined to face each other,the aboveConcave
This forms an article storage space.

[0016] With the above configuration, for example, if the impact is applied from the outside of the packaging structure to accommodate foods, flexures toward the bottom cushioning body constituting the packaging structure is at least the side or sides To absorb external shocks. As a result, external impact is not transmitted directly to the article, and the article is protected from damage.

Further, since the packaging cushion according to the present invention can protect the article from impact only by sandwiching the article between the packaging cushions, it uses a piece of paper such as newsprint or an air cushion for packaging. Compared with the conventional method of buffering articles, the article can be stored easily without any trouble.

The concave cardboard member is made of paper material.
Since it is formed, unlike a packaging buffer body made of foamed plastic, no harmful gas is generated even when incinerated after use, so there is no environmental problem.

In the case of a packaging cushion in which means for fixing an article is provided on the side of a corrugated cardboard member , the article is fixed even if an external impact is applied. There is no danger that the goods will move and be damaged.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the embodiments shown in the drawings. FIG. 1 is a perspective view showing an embodiment of the packaging cushion according to the present invention, FIG. 2 is a front view of the packaging cushion shown in FIG. 1 viewed from the direction of arrow I, and FIG. It is a perspective view which shows the member made from cardboard which is a component. Reference numeral 50 denotes a packaging buffer. The packaging cushion 50 is configured using a pair of corrugated cardboard members 5 that are concave members.

With reference to FIG. 3, the cardboard member 5, which is a constituent member of the packaging cushion 50, will be described. The cardboard member 5 has a concave surface 51. The concave surface 51 is constituted by a bottom portion 511 and a side portion 512 having a gentle gradient, and is formed to be slightly curved from the side portion 512 to the bottom portion 511.

The cardboard member 5 is obtained by pressing and molding a double-sided cardboard. However, the bottom surface 511 of the concave surface 51 of the corrugated cardboard member 5 is not substantially pressed by a press , and the cushioning property of the corrugated cardboard itself, which is a material, is not impaired. This allows
The bottom portion 511 of the cardboard member 5 has a sufficient thickness and excellent cushioning properties. The bottom 5 of the cardboard member 5
11 can also be pressed to form the entire corrugated cardboard member 5 hard and with increased strength. The method of forming the cardboard member 5 will be described later.

Then, two of the cardboard members 5 are used, and the bottom 511 is formed so that the concave surface 51 faces outward.
Outer allowed to adhere to each other by integrating them, the cushioning member 5
0 (see FIGS. 1 and 2). Hereinafter, of the pair of corrugated cardboard members 5 constituting the cushioning member 50 for packaging, the one that constitutes the accommodation space for the article is referred to as “accommodating member 5a” (upper side in FIG. Member 5b "
(Lower side in FIG. 1). "

[0024] The four corners of the middle portion of the side 512 of the housing member 5a, switching write unit 52 for securing the article to the housing space is formed. Switching write unit 52, the external shape of the accommodated articles are cut into various shapes. The housing member 5
In the peripheral portion of a, two cuts 531 constituting the locking piece 53 are formed at two locations on one side in the longitudinal direction and one location on both sides in the lateral direction, and are formed slightly diagonally toward the outer peripheral side. The cutouts 531 are arranged so as to be vertically overlapped when the pair of packaging shock absorbers 50 are combined so that the concave surfaces 51 face each other.

(Operation) FIG. 4 is an explanatory view of the use state of the packaging cushion. With reference to FIG. 4, a case where a portable information terminal device (hereinafter abbreviated as a product) is packed by the packing buffer 50 will be described as an example. The product 6 is sandwiched between a pair of packaging cushions 50.
At this time, the concave surface of the switching write portion 52 is formed housing member 5a 5
1 side is opposed, the product 6 is to be fixed to the switching write <br/> portion 52 that is formed on the side 512 four places. Then, after overlapping and combining the cushioning bodies 50 for packaging, the cuts 531,
The locking piece 53 formed by 531 is folded in the same direction,
The packaging cushions 50 are fixed so as not to shift. In order to separate the packaging cushions 50, 50 fixed in combination again, the folded locking pieces 53 may be returned to the original state.

FIG. 5 is a longitudinal sectional view showing a state in which the product protected by the packaging cushion is accommodated in the packaging box.
Referring to FIGS. 4 and 5, the operation of the packaging structure 70 configured cushion 50 and thereby packaging.
Packaging structure 70 includes a pair of the cushioning member 50 for protecting across the product 6, the packaging box 7 without any gap accommodates a pair of cushioning member 50. The product 6 includes a packaging cushion 50 constituted by a pair of cardboard members 5 (a housing member 5a and a holding member 5b) inside the packaging box 7.
It is held in the accommodating space 8 by which, switching write unit 52 is protected by.

With the above structure, for example, when an impact is applied from the outside of the packaging box 7 containing the product 6, the side part 512 of the holding member 5b constituting the packaging cushion 50 is moved inward as shown by the arrow. By acting as a cushion by flexing to the side, the shock is absorbed and the product 6 is prevented from being damaged.

Further, since the product 6 can be protected from impact only by sandwiching the product 6 between the pair of packaging cushions 50, 50, a conventional product using a piece of paper such as newsprint or an air cushion for packaging. The product 6 can be easily accommodated without any trouble compared to the method of buffering articles.

Also, the product 6 is protected by two spaces: a housing space 8 for housing the product 6, and a space 9 formed by the concave surface 51 of the holding member 5b and the packaging box 7. Is hard to transmit directly to the product 6. Note that product 6, because it is secured by the switching write unit 52, there is no risk that the product 6 in the accommodating space 8 is moving damage.

Further, since the packaging buffer 50 is made of corrugated cardboard, unlike a packaging buffer made of foamed plastic, no harmful gas is generated even when incinerated after use. There is no environmental problem.

The pair of packaging cushions 50, 50, which sandwich and accommodate the product 6, can be used as a packaging container by themselves, without being further packaged in the packaging box 7. That is, for example, if the packaging cushion 50 is used, the personal computer can be carried in a weak leather bag, for example, without using a carrying bag dedicated to a notebook personal computer.

Next, a method of manufacturing the cardboard member 5 constituting the packaging cushion 50 will be described. The cardboard member 50 can be manufactured by a cardboard member manufacturing apparatus A described below. 6 is a perspective view of a cardboard member manufacturing apparatus, FIG. 7 is a perspective view of a main part showing a structure of a molding die,
FIG. 8 is a sectional view of a main part showing the structure of the pressing die. The structure of the cardboard member manufacturing apparatus will be described with reference to FIGS. Reference numeral A denotes a corrugated cardboard member manufacturing apparatus provided with a frame 1. The frame 1 includes an H-shaped base member 10, four leg members 11 erected on the base member 10, and an upper frame 12 provided thereon.

At the center of the base member 10, a metal mold base 30 is provided.
have. The mold table 30 is heated by an electric heater (not shown), and heats a mold 31 described below. A rectangular mounting recess 300 is formed on the upper surface of the mold base 30, and a wooden mold 31 is mounted in the mounting recess 300. At the center of the surface of the molding die 31, a step 320 having a rectangular shape lower by one step is formed, and at the center of the step 320, a mold part 32 formed to be concave in the lower surface shape of the cardboard member is formed. It is provided. Since the mold 31 is made of wood, it can be manufactured relatively inexpensively.
In addition, other materials, such as metal, can also be employ | adopted for the shaping | molding die 31.

Air vent holes 33 are provided at the four corners at the bottom of the mold portion 32, respectively. The air vent hole 33 communicates with an air passage 34 provided in the mold 31 and connected to an air suction device (not shown).

The pressing die 2 is provided above the forming die 31. The pressing die 2 includes an inner die 27 provided inside and a pressing body 20 provided around the inner die 27. The inner mold 27 is a solid body, and is fixed to the lower surface side of a rectangular pressing board 21 made of metal. The surface shape of the inner mold 27 is a planar shape that is almost in contact with the upper surface of the corrugated cardboard as a material and hardly pressed when the pressing mold 2 is lowered to form the corrugated cardboard member.

The pressing body 20 is formed in a bag shape from a flexible rubber sheet, and is attached to the pressing substrate 21 so as to surround a side portion of the inner mold 27 in an appropriately expanded state. The thickness of the sheet is 2 mm. On the lower surface side of the pressing substrate 21, a far-infrared heater (not shown) is attached so as to be included in the pressing body 20. The pressing body 20 is heated by a far-infrared heater using the air inside as a medium. Also,
The pressing body 20 can expand and contract by adjusting the supply of air from an air supply device (not shown).

The pressing substrate 21 is attached to the lifting plate 23 by two coil springs 22. Lifting plate 23
Is attached to the rod head of the air cylinder S.
The air cylinder S is provided vertically at the center of the upper frame 12 via a base plate 13 with the rod head facing downward. It should be noted that other means such as a hydraulic cylinder and a ball screw can be adopted as the driving means of the pressing body 20. A guide plate 24 is provided upright on the front edge of the pressing substrate 21, and the guide plate 24 is provided with an elongated guide hole 25 in the vertical direction. Pins 26 provided at the front and rear edges of the elevating plate 23 are inserted into the guide elongated holes 25, so that the pressing substrate 21 and the pressing body 20 can move up and down without laterally shifting. Reference numeral 14 denotes an operation panel.

(Operation) FIG. 9 shows a method of manufacturing a cardboard member, and is a cross-sectional explanatory view showing a state before pressing a cardboard sheet. FIG. 10 shows a method of manufacturing a cardboard member. FIG. 11 is a cross-sectional explanatory view showing a method of manufacturing a cardboard member, showing a state in which a molded cardboard sheet is being released from a mold.

With reference to FIGS. 5 to 11, a method for manufacturing a cardboard member using cardboard as the material by the cardboard member manufacturing apparatus A will be described. The corrugated cardboard used as the material may be a double-sided corrugated cardboard in which cardboard is bonded to both sides of a corrugated middle paper, or a single-sided cardboard in which cardboard is adhered to only one side. (1) The mold base 30 is heated to heat the mold 31 to 70 to 80 ° C., and the pressing body 20 is moved to about 100
Heat to ° C. Note that this temperature is not limited to the above temperature, and can be set as appropriate. (2) The cardboard sheet 500 as a material is fitted and placed on the step 320 of the molding die 31.

(3) The air cylinder S is actuated to lower the pressing die 2 so that the surface of the inner die 27 is
The cardboard sheet 500 in the step portion 320 is lightly pressed by the pressing member 20 in a slightly inflated state and pressed against the mold portion 32 while not being pressed against zero. (4) Supply air to the pressing body 20 by an air supply device,
The pressing body 20 is expanded. At the same time, the air suction device is operated to suck the air between the corrugated cardboard sheet 500 and the mold section 32 from the air vent hole 33 to make it almost vacuum, thereby bringing the corrugated cardboard sheet 500 and the mold section 32 into close contact.

(5) Since the molding die 31 and the pressing body 20 are heated to the predetermined temperature as described above, the corrugated cardboard sheet 500 sandwiched and pressed by both sides is also heated and easily deformed. . Then, the corrugated cardboard sheet 500 is pressed by the surface pressure of the pressing body 20 which expands by supplying air.
Of these, the portion excluding the portion in contact with the inner mold 27 is pressed against the mold portion 32 to be molded. The pressing body 20 can press the entire surface of the molded portion of the corrugated cardboard sheet 500 from the upper surface with substantially uniform pressure, and can be deformed along the shape of the mold portion 32. Then, the pressing body 20 is moved to the cardboard sheet 5.
When pressing 00 on the mold part 32, since the mold part 32 is a female mold, first, the cardboard sheet 500 is strongly pressed at the edge of the mold part 32 and is almost fixed. In this state, the pressing body 2
0 is expanded and pressed while deforming the corrugated cardboard sheet 500 and finally brought into close contact with the surface of the mold portion 32. As a result, the excess material is not drawn into the mold portion 32 and the pressing body 20 gradually expands, so that wrinkles hardly occur even at the rounded portions at the four corners where the deformation amount is large. The bottom 511 of the cardboard member of the cardboard sheet 500
Is not pressed, the thickness of the material remains as it is, and the cushioning property is not impaired. Therefore,
The bottom portion 511 does not become hard, and a sufficient cushioning property as a packaging cushion can be secured, and the function of absorbing an external impact is excellent.

(6) The presser body 20 is deflated by bleeding air,
To raise. Then, the corrugated member-shaped concave portion 50 is formed.
Is removed from the mold 31. Then, by naturally cooling and cutting off unnecessary portions of the edges as necessary, a corrugated cardboard member having a thick bottom portion 511 (concave portion) and a thin side portion can be produced. it can. Since the cardboard member is heated and pressed, the shape retention is good, and the shape does not return to the original flat shape after cooling.

It is also possible to press the portion of the corrugated cardboard member 500 which becomes the bottom portion 511 of the corrugated cardboard member, so that the entire corrugated cardboard member can be formed hard and with improved strength.

FIG. 12 is a sectional explanatory view showing another method of manufacturing a cardboard member, showing a state before pressing a cardboard sheet. In the drawings, the same or equivalent parts as those shown in FIG. 9 are denoted by the same reference numerals. In the present embodiment, the mold 31 has an air vent hole 33.
And the ventilation path 34 are not provided (the apparatus for manufacturing a corrugated cardboard member related to the mold 31 does not include an air suction device). The surface of the corrugated cardboard sheet 500 is relatively rough, and the molding die 31 is also made of wood. Therefore, the degree of sealing of both contact surfaces does not become too high, and air easily escapes during the press working, which hinders the work. Absent.

Further, a slip sheet 4 for improving the slip of the corrugated cardboard sheet 500 is placed near the edge of the mold portion 32 of the molding die 31. The lubricating sheet 4 is obtained by subjecting a very thin synthetic resin sheet to Teflon processing. According to this structure, when a predetermined or more pressing force is applied to the fixed portion of the cardboard sheet 500 at the edge of the mold portion 32 by the pressing body 20, the fixed portion can move toward the inside of the mold portion 32, 500 can be prevented, and the production yield can be improved.

The terms and expressions used in the present specification are for explanation only, are not restrictive, and do not exclude terms and expressions equivalent to the above-mentioned terms and expressions. Further, the present invention is not limited to the illustrated embodiment, and various modifications are possible within the scope of the technical idea.

[0047]

The present invention has the above configuration and has the following effects. (A) The cushioning body for packaging according to the present invention comprises a bottom and a periphery of the bottom.
And a sloped side formed in the enclosure
Provided with two corrugated cardboard members having recessed concave surfaces.
The two pieces made of metal have the bottom side
It is provided in combination so that each faces outward,
In the corrugated cardboard member, a space is formed by the concave surface
And at least from the side or from the side to the bottom
It has flexibility. And the loosening for packaging according to claim 2
The impulse is a pair of cushioning bodies for packaging according to the invention of claim 1.
Made, the buffer bodies combined so as to face the concave side, the housing space of the article by the concave surface is formed. With the above configuration, for example, if an impact is applied from the outside of the packaging structure <br/> granulated body containing the article, the bottom cushioning body constituting the packaging structure is at least the side or sides And absorbs external impact. As a result, external impact is not transmitted directly to the article, and the article is protected from damage. Further, the packaging cushion according to the present invention can protect the article from impact only by sandwiching the article between the packaging cushions, so that a paper piece such as newsprint or an air cushion for packaging can be used. Compared to the conventional method of buffering articles used, articles can be stored easily without any trouble.

[0048] (b) the cushioning body is different from the cushioning material formed of a foamed plastic, even if incinerated after use, since the harmful gas is not generated, there is no environmental problem.

(C) In the case of a packaging cushion in which means for fixing an article is provided on the side of a cardboard member ,
Even if an external impact is applied, since the article is fixed, there is no danger that the article will move and be damaged in the accommodation space.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a packaging cushion according to the present invention.

FIG. 2 is a front view of the packaging cushion shown in FIG.

FIG. 3 is a perspective view showing a cardboard member which is a constituent member of the packaging cushion.

FIG. 4 is an explanatory view of a use state of the packaging cushion.

FIG. 5 is a longitudinal sectional view showing a state in which a product protected by the packaging cushion is accommodated in a packaging box.

FIG. 6 is a perspective view of a cardboard member manufacturing apparatus.

FIG. 7 is a perspective view of a main part showing a structure of a molding die.

FIG. 8 is a sectional view of a main part showing a structure of a pressing die.

FIG. 9 is a cross-sectional explanatory view showing a method of manufacturing a cardboard member and showing a state before pressing a cardboard sheet.

FIG. 10 is an explanatory sectional view showing a method of manufacturing a cardboard member and showing a state in which a cardboard sheet is being pressed.

FIG. 11 is a cross-sectional explanatory view showing a method of manufacturing a cardboard member, and showing a state in which a molded cardboard sheet is being released from a mold.

FIG. 12 is an explanatory sectional view showing another method of manufacturing a cardboard member, and showing a state before pressing a cardboard sheet.

[Explanation of symbols]

 A Corrugated cardboard member manufacturing apparatus 1 Frame 10 Base member 11 Leg member 12 Upper frame 13 Base plate 14 Operation panel 2 Press type 20 Press body 21 Elevating plate 22 Coil spring 23 Press substrate 24 Guide plate 25 Guide slot 25 Pin 27 Inner die S Air cylinder 30 Mold base 300 Mounting concave part 31 Mold 32 Mold part 320 Step part 33 Air vent hole 34 Air passage 4 Slip sheet 5 Cardboard member 51 Concave surface 511 Bottom part 512 Side part 52 Cut part 53 Lock piece 531 Cut part 5a Housing member 5b Holding member 50 Packaging buffer 500 Corrugated cardboard sheet 6 Product 7 Packaging box 70 Packaging buffer 8 Housing space 9 Space

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B65D 81/113 B65D 85/86 B65D 5/50 101

Claims (5)

(57) [Claims] A bottom (511) and a periphery formed around the bottom (511).
And sloped sides (512)
The two corrugated cardboard members (5) each having a concave surface (51) are provided, and the two corrugated cardboard members (5) are in contact with the bottom (511) outside and the concave (51) sides are outside. The corrugated cardboard member (5) is provided with a space by the concave surface (51).
Part is formed and at least the side (512) or the side (51
It has flexibility from 2) to the bottom (511), and the concave surface (51) has the flexibility to expand by air supply.
Table when the pressing body made of rubber sheet
A cushioning material for packaging, characterized by being formed by surface pressure . 2. A pair of packaging cushions according to claim 1.
Made, the damping body (50) is concave (51) side combined so as to face the accommodation space of the article by the concave surface (51) (8)
A cushioning material for packaging, characterized in that: 3. The cushioning body for packaging according to claim 1, wherein a means for fixing an article is provided on a side portion (512) of the cardboard member (5) . 4. The means for fixing an article includes a notch (5)
4. The packaging cushion according to claim 3, wherein the cushioning body comprises: 5. The method of claim 1, characterized in that it comprises a packaging box for packaging the 2, 3 or 4 cushioning body according (7), the packaging structure.