JP4801408B2 - Cup-shaped paper container - Google Patents

Description

  The present invention relates to a structure for preventing leakage of a cup-shaped paper container made of a base paper laminated with a polyester resin.

Conventionally, a paper cup made of a base paper laminated with a polyester resin has been used in ovens and microwave ovens such as gratin and cake.
In addition to heat resistance, this type of paper cup has the advantages of less odor of the resin itself and less adsorption of liquid scent components, and is also required as a container for containing liquid.
However, as shown in FIG. 5, the paper cup has a bonding portion between a side seal portion in the trunk portion vertical direction (trunk side seam portion 11) and a bottom seal portion 12 in the circumferential direction of the bottom portion 7.
And as shown in FIG. 6, since the trunk | drum side seam part 11 is wound and bonded so that the edge part of a trunk | drum blank may be piled up, a level | step difference is formed inside.
Since the bottom portion 7 is fitted inside the barrel portion 5 to perform bottom sealing, a gap 9 is formed in the bottom step portion 8 where the step of the barrel side seam portion 11 and the bottom seal portion 12 intersect with each other. The filled liquid may leak out from the gap.
In order to prevent the liquid from leaking, it is necessary to fill the bottom step portion when molding the paper cup.
In conventional polyethylene paper cup was laminated with the base paper and materials, is of about 110 ° C. The melting point of the polyethylene, so easy to flow well heat-sealing properties, Po triethylene into the gap 9 of the bottom step part 8 at bottom seal Was able to fill and fill.
However, in the case of a polyester resin, the melting point is 200 ° C. or higher, and the gap between the bottom stepped portions 8 cannot be sufficiently filled at the time of bottom sealing, and there is a drawback that a leakage path is generated.
Although this leakage path can be solved to some extent by folding the lower end of the body part and wrapping the peripheral wall of the bottom part, it has not been a fundamental solution.
Japanese Patent Laid-Open No. 10-53238

  The present invention has been made in view of the above-mentioned circumstances, and the main problem is that in a cup-shaped paper container made of a base paper laminated with a polyester resin, a portion where the trunk side seam portion and the bottom seal portion at the bottom intersect each other It is an object of the present invention to provide a cup-shaped paper container in which a gap between the bottom stepped portions formed in the container is filled so as not to cause a leakage path.

In order to solve the above problem, the invention of claim 1
A trunk blank of a cup-shaped paper container having a paper layer made of base paper, an inner surface second layer laminated on the inner surface side of the paper layer, and an inner surface first layer laminated on the inner surface side of the inner surface second layer In a cup-shaped paper container using
The inner surface first layer consists of a polyester resin layer made of a Homo-PET resin or a copolymerized PET resin, or a polyester resin layer to which a low melting point resin having a lower melting point than the polyester resin is added,
The inner surface second layer is made of a low melting point resin having a lower melting point than the inner surface first layer,
The part where the inner surface side is notched to a predetermined thickness at the end which is the inner side of the body side seam part heat-sealed in the vertical direction when the body part is formed, and the remaining part is folded back and cut off A polyester resin is applied so as to cover and close the end surface of the blank end portion which becomes the inner surface side when the body portion is formed, or the sky bar processing portion where the inner surface second layer is covered inside the inner surface first layer. And forming a resin coating portion to block the end face from being exposed with a polyester resin,
The inner surface second layer melts before the inner surface first layer or the polyester resin of the resin coating portion at the time of bottom sealing through a gap formed at the bottom seal portion of the bottom of the cup-shaped paper container inside the trunk side seam portion. The inner surface first layer or the resin is interlocked so that the inner surface second layer is not exposed in a state of being covered by the inner surface first layer .
In the invention of claim 2,
The inner surface second layer is made of LDPE, LLDPE, or EMA.
Furthermore, in the invention of claim 3,
The inner surface first layer is made of a polyester resin layer having a lower melting point than that of the polyester resin and a low melting point resin having a melting point of 90 to 140 ° C. mixed in an amount of 1 to 30% by weight.
In the invention of claim 4,
The low melting point resin added to the polyester resin layer of the first inner surface layer is an ionomer resin.
In the invention of claim 5,
An outer surface layer made of a polyester resin or a coating material made of Homo-PET resin or copolymerized PET resin is laminated on the outer surface side of the paper layer.
Furthermore, in the invention of claim 6,
The cup-shaped paper container uses a moving mandrel that moves and heats the mandrel when the two ends of the body part are wound and joined so as to overlap each other.
The bottom paper that closes the bottom of the body portion is integrally formed from a flat plate portion and an outer peripheral edge of the flat plate portion, and is formed of an annular and narrow margin portion, and the margin portion of the bottom paper covers the lower end of the body portion. Folded and pinched, bottom curled, the bottom sealed part is crimped, and the bottom paper is integrally joined to the trunk,
The pressure bonding method is characterized by comprising a rotary pressure bonding method in which pressure is applied while rotating along an inner peripheral surface or an expander method in which pressure is applied in a radial direction.

  In this invention, even a base paper laminated with a polyester resin is provided with a low melting point resin layer between the paper layer and the polyester resin layer, so that the polyester resin layer is formed through the low melting point resin layer melted at a low temperature. It can be moved to fill the gap in the bottom stepped portion and block the leakage path, thereby preventing the liquid in the container from leaking.

A preferred embodiment in which the cup-shaped paper container of the present invention is applied to a paper cup will be described below with reference to the drawings.
As shown in FIG. 5, the paper cup 10 is fitted into a cylindrical body 5 having a body side seam portion 11 by heat-sealing the end of the body blank 6 in the vertical direction and a lower portion of the body 5. It has a shape having a bottom seal portion 12 where the bottom 7 is heat sealed.

As shown in FIG. 2A, when the end portion of the body blank 6 is overlapped and side-sealed to form the body side seam portion 11, a stepped portion is formed on the inside, and when the bottom of the cross-section channel shape is fitted, the above-described body A bottom step 8 is formed at a location where the side seam 11 intersects.
Therefore, when the bottom portion 7 is welded by the bottom seal, the vicinity of the bottom step portion 8 is heated, and the gap 9 of the bottom step portion 8 is filled with resin as will be described later, thereby eliminating the leakage path.

As a raw material configuration of the paper cup 1, the material configuration of the body blank 6 is as follows (see FIG. 1).
Polyester resin layer 1 (inner surface first layer) / low melting point resin layer 2 (inner surface second layer) / paper layer 3 / outer surface layer 4
(1) Polyester resin layer 1 (inner surface first layer)
Any polyester resin may be used, but in this example, either Homo-PET (homopolymer polyethylene terephthalate) or copolymerized PET (copolymer polyethylene terephthalate) can be used.

In the polyester resin layer 1, it is preferable that a low melting point resin having a temperature of 90 to 140 ° C. is mixed with the polyester resin in an amount of 1 to 30% by weight because the low temperature heat sealability is excellent and the leakage preventing effect is high.
Here, the low melting point resin to be mixed is a resin having a lower melting point than that of the polyester resin. By mixing this resin, the melting point of the polyester resin layer 1 can be slightly lowered, and the fluidity during heating can be increased. .

(2) Low melting point resin layer 2 (inner surface second layer)
A resin having a melting point lower than that of the polyester resin layer 1 is used.
For example, it is practically preferable to use LDPE (low density polyethylene), LLDPE (linear low density polyethylene), or EMA (ethylene / methacrylic acid copolymer resin), and LLDPE is particularly preferable.
The melting point is desirably in the range of 70 to 140 ° C.
The low melting point resin layer 2 starts to melt and move before the polyester resin layer 1 during heating such as a bottom seal, and interlocks with the polyester resin layer 1 to fill the gap 9 in the bottom stepped portion 8 and block the leakage path. (See FIG. 2B).

(3) Paper layer 3
As the paper layer 3, a known paperboard for paper containers (as an example, a basis weight of 100 to 500 g / m ² ) is used.

(4) Outer surface layer 4
The outer surface layer may or may not be provided.
When the outer surface layer 4 is provided, a polyester resin or a coating material is used.
Here, it is preferable to use Homo-PET or copolymerized PET as the polyester resin.

The body blank 6 formed in a fan shape so as to form the body 5 is preferably subjected to a skive treatment on an end surface which is an inner surface side or a resin is applied to the end surface to seal the cross section.
These can be appropriately designed according to the use of the cup.
Thereby, the end surface of the trunk blank is not exposed, which is beneficial for hygiene.

FIG. 3 is a cross-sectional view illustrating the skive process.
Reference numeral 15 denotes a sky bar processing portion, and when the end of the body blank 6 is overlapped and side-sealed, the end portion 6a on the inner surface side is cut out to a substantially half thickness, and the half thickness is left. The structure is constructed such that the end portion is folded outward and the cut-out portion is overlapped and adhered without gap so that the end face is not exposed.

FIG. 4 is a cross-sectional view illustrating a resin coating process.
Reference numeral 16 denotes a resin coating, which has a structure in which the end face is not exposed by applying a resin coating so as to cover and close the end face on the inner face side when the body blank 6 is side-sealed.
At this time, it is necessary that the inner surface side seam end surface has resin.

  The material configuration of the bottom blank forming the bottom portion 7 may be the same as that of the body blank 6 or a three-layer structure of polyester resin layer 1 / base paper 3 / outer surface layer 4 with the low melting point resin layer 2 omitted. May be.

  Next, using the body blank and the bottom blank, the paper cups for tests 1 to 7 of the control product and the practical product are respectively molded, and a leakage inspection liquid containing a surfactant is put into those paper cups up to the 8th minute of the paper cup, After leaving for 20 minutes, leakage was confirmed.

[Test 1]
Body blank configuration (reference product 1)
Polyester resin layer 1 exHomo-PET
Low melting point resin layer 2 None Paper layer 3 Basis weight 250 g / m ²
Outer surface layer None Bottom blank configuration Same as body blank End surface treatment None Leakage inspection result (number of leaks / number of inspections) 70/500

[Test 2]
Body paper composition (reference product 2)
Polyester resin layer 1 exHomo-PET
Low melting point resin layer 2 None Base paper 3 Basis weight 250 g / m ²
Outer surface layer None Bottom blank configuration Same as trunk blank End surface treatment Skybar treatment Leakage inspection results (number of leaks / number of inspections) 10/500

[Test 3]
Body blank configuration (reference product 3)
Polyester resin layer 1 exCo-PET
Low melting point resin layer 2 None Base paper 3 Basis weight 250 g / m ²
Outer surface layer None Bottom blank configuration Same as trunk blank End surface treatment Skybar treatment Leakage inspection result (number of leaks / number of inspections) 5/500

[Test 4]
Body blank configuration (reference product 4)
Polyester resin layer 1 Co-PET (with low melting point resin)
Low melting point resin layer 2 Adhesive base paper Basis weight 250 g / m ²
Outer surface layer None Bottom blank configuration Same as the body blank End surface treatment Polyester resin coating Leak inspection result (number of leaks / number of inspections) 2/500

[Test 5]
Body blank configuration (product 1)
Polyester resin layer 1 Co-PET (with low melting point resin)
Low melting point resin layer 2 LLDPE
Paper layer 3 Basis weight 250g / m ²
Outer surface layer None Bottom blank configuration Same as test 4 body blank End treatment Polyester resin coating Leak inspection result (number of leaks / number of inspections) 0/1000

[Test 6]
Body blank structure (product 2)
Polyester resin layer 1 Co-PET (with low melting point resin)
Low melting point resin layer 2 LLDPE
Paper layer 3 Basis weight 250g / m ²
Outer surface layer 4 exHomo-PET
Bottom blank structure Same as the body blank of Test 4 End treatment Polyester resin coating Leakage inspection results (number of leaks / number of inspections) 0/1000

[Test 7]
Body blank configuration (product 3)
Polyester resin layer 1 Co-PET (with low melting point resin)
Low melting point resin layer 2 LLDPE
Base paper Basis weight 250g / m ²
External layer exHomo-PET
Bottom blank structure Same as test 4 body blank End face treatment Sky bar treatment Leak inspection result (number of leaks / number of inspections) 0/1000

In the test of the above-mentioned product, an ionomer resin was used as a low melting point resin blended with the polyester resin layer 1. Specifically, “High Milan (registered trademark)” (sold by Mitsui DuPont Polychemical Co., Ltd.) was used. The mixing amount is in the range of 1 to 30% by weight, but is preferably used in the range of 18 to 20%.
Further, the material of the low melting point resin layer 2 may be any of LDPE, LLDPE, or EMA, but LLDPE hardly causes a neck-in phenomenon.

Next, when forming the paper cup, the body blank is formed into a cylindrical shape by a body forming device along the mandrel by a known method, and the edge portion serving as the side seal portion is heat sealed.
Then, the inner peripheral surface and the bottom portion of the body portion are heated to heat-seal the portion that becomes the bottom seal portion.

  In the test of the above-mentioned product, if the mandrel (moving mandrel) is moved during heat sealing with high-temperature hot air, the polyester resin layer and the low-melting resin layer are efficiently heated, and the low-melting resin The layer or the PET resin could be reliably melted, and the leak test result could be improved to 0/10000.

This cup molding method will be described with reference to FIGS.
In the present embodiment, it is preferable to use the moving mandrel as the cup molding device as described above.
In the case of a normal mandrel, as shown in FIG. 7A, heating with hot air is performed a plurality of times (three times in the illustrated example) through the bottom paper at the bottom seal portion (a-1 to a-3). In FIG. 7, 20 is a base paper, 30 is a bottom paper which becomes the bottom of the cup, 31 is a flat part, 32 is bent integrally from the outer peripheral edge of the flat plate part 31, and is set to be annular and narrow. The part and the arrow indicate the heating position.

On the other hand, in the moving mandrel, as shown in FIG. 7 (b), the position of the bottom paper 30 is set above the trunk base paper 20, and a plurality of times (illustration example) is provided at the bottom seal corresponding portion 12 'of the trunk section 20. Then, heating is performed twice (b-1, b-2), and the bottom paper 30 is then moved at a position where the base paper 20 is raised and the bottom paper 30 is relatively lowered (position shown in FIG. 7A). (B-3).
Then, as shown in FIG. 7C, the lower end of the trunk base paper 20 is folded back, the marginal portion 31 is sandwiched and the bottom curl is performed, and the bottom seal is performed.

Next, the bottom seal portion is crimped.
The crimping method includes a roll-out (rotary crimping) method and an expander method.
In the roll-out method, as shown in FIGS. 8A and 8B, the roller-shaped pressurizer 40 is pressed and coupled along the inner peripheral surface that becomes the bottom seal portion 12 at the bottom of the cup.

In the case of the expander method, as shown in FIGS. 9A and 9B, a pressurizer 40 ′ having a substantially fan-shaped cross section divided into a plurality of sections (four sections in the illustrated example) is radially outward from the center. The bottom seal portion 12 at the bottom of the cup is pressurized in a radial manner (a-1).
In the illustrated example, the pressurizer 40 'is rotated 45 degrees (the body portion may be rotated), and the pressure is applied without a gap (a-2).
Any crimping method may be used, but the expander method is preferable because no force in the rotational direction is applied to the crimping portion.

  Of course, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the scope of the present invention.

It is sectional drawing which shows an example of a trunk | drum blank. It is principal part sectional drawing which shows the state where the bottom step part was buried and the leak path | route was lose | eliminated. It is a figure explaining a sky bar process, (a) is a front view of a trunk | drum blank, (b) is a top view, (c) is sectional drawing to which the edge part was expanded. It is a figure explaining the process coat | covered with resin, (a) is a front view of a trunk | drum blank, (b) is a top view, (c) is sectional drawing to which the edge part was expanded. It is a perspective view of a paper cup. It is a principal part enlarged view which shows the clearance gap between the bottom step parts of the conventional paper cup. It is a heating system using a mandrel, (a) is a normal mandrel, (b) is a moving mandrel, and (c) is a diagram for explaining a bottom curl. (A) is a top view which shows the crimping | compression-bonding system by rollout, (b) is the same sectional drawing. (A) is a top view which shows an expand system, (b) is the same sectional drawing.

Explanation of symbols

1 Polyester resin layer (inner surface first layer)
2 Low melting point resin layer (inner surface second layer)
3 Paper layer 4 External layer 5 Body part 6 Body part blank 7 Bottom part 8 Bottom step part 10 Paper cup 11 Body side seam part (Cylinder side seal part)
12 Bottom seal part 15 Sky bar processing part 16 Resin coating part 20 Body base paper 30 Bottom paper 31 Flat part 32 Margin 40, 40 'Pressurizer

Claims (6)

A trunk blank of a cup-shaped paper container having a paper layer made of base paper, an inner surface second layer laminated on the inner surface side of the paper layer, and an inner surface first layer laminated on the inner surface side of the inner surface second layer In a cup-shaped paper container using
The inner surface first layer consists of a polyester resin layer made of a Homo-PET resin or a copolymerized PET resin, or a polyester resin layer to which a low melting point resin having a lower melting point than the polyester resin is added,
The inner surface second layer is made of a low melting point resin having a lower melting point than the inner surface first layer,
The part where the inner surface side is notched to a predetermined thickness at the end which is the inner side of the body side seam part heat-sealed in the vertical direction when the body part is formed, and the remaining part is folded back and cut off A polyester resin is applied so as to cover and close the end surface of the blank end portion which becomes the inner surface side when the body portion is formed, or the sky bar processing portion where the inner surface second layer is covered inside the inner surface first layer. And forming a resin coating portion to block the end face from being exposed with a polyester resin,
The inner surface second layer melts before the inner surface first layer or the polyester resin of the resin coating portion at the time of bottom sealing through a gap formed at the bottom seal portion of the bottom of the cup-shaped paper container inside the trunk side seam portion. The cup is characterized in that it is made to flow so as to close the gap, and the inner surface first layer or the resin is interlocked so that the inner surface second layer is not exposed when covered with the inner surface first layer. Paper container.   The cup-shaped paper container according to claim 1, wherein the second inner layer is made of LDPE, LLDPE, or EMA.   The inner surface first layer is composed of a polyester resin layer having a melting point lower than that of a polyester resin and a low melting point resin having a melting point of 90 to 140 ° C mixed in an amount of 1 to 30% by weight. The cup-shaped paper container as described.   4. The cup-shaped paper container according to claim 1, wherein the low melting point resin added to the polyester resin layer of the first inner layer is an ionomer resin.   4. The cup shape according to claim 1, wherein an outer surface layer made of a polyester resin or a coating material made of Homo-PET resin or copolymerized PET resin is laminated on the outer surface side of the paper layer. Paper container. The cup-shaped paper container uses a moving mandrel that moves and heats the mandrel when the two ends of the body part are wound and joined so that they overlap each other.
The bottom paper that closes the bottom of the body portion is integrally formed from a flat plate portion and an outer peripheral edge of the flat plate portion, and is formed of an annular and narrow margin portion, and the margin portion of the bottom paper covers the lower end of the body portion. Folded and sandwiched, the bottom seal part was crimped, and the bottom paper was integrally joined to the body,
6. The cup shape according to any one of claims 1 to 5 , wherein the crimping method is a rotary crimping method in which pressure is applied while rotating along an inner peripheral surface or an expander method in which pressure is applied in a radial direction. Paper container.

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