JPH05330560A - Bag-in-box and bag used therefor - Google Patents

Abstract

PURPOSE:To obtain a bag which is excellent in heat-seal property during bag making and has both mechanical strength and heat-resistance, by a method wherein the bag is made of a specified laminated film by heat-sealing and a layer to be heat-sealed includes a layer containing specified linear low-density polyethylene. CONSTITUTION:A bag-in-box consists of a paper-made box 10 and a resin film- made bag 20 which is placed in the box 10. The bag 20 is made of a laminated film by heat-sealing and the laminated film consists of inner and outer layers of olefin resin and an intermediate layer of ethylene vinyl alcohol copolymer. At least one of the inner and outer layers, whichever is heat-sealed, is composed of a layer containing linear low-density polyethylene having a density of 0.915g/cm<3> or less and a melting point of 110 deg.C or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back-in-box and a bag used therefor, and more particularly to a heat-sealing portion at the time of hot filling in a bag using an ethylene vinyl alcohol copolymer intermediate layer. The present invention relates to an improvement of a bag that prevents the retreat and peeling of the bag and prevents edge breakage due to a drop impact or the like.

[0002]

2. Description of the Related Art A bag-in-box in which a bag for filling contents formed of a plastic film or a laminate having the film as a constituent material is housed in a carton box is a container for sealing various liquid contents. It is widely used in the distribution stage as a packaging container for packaging and transporting, and has the advantage of relatively low packaging cost and easy disposal.

Since the carton box is a rectangular parallelepiped, it is desired that the bag for filling the contents also has a substantially rectangular parallelepiped shape that fits (fits) exactly in the contents-filled state. Further, this bag is desired to have oxygen permeation resistance from the viewpoint of storability of contents.

From these requirements, as a film material constituting a bag, a multilayer film in which a heat-sealable resin, especially an inner and outer layer of an olefin resin is laminated on an ethylene vinyl alcohol copolymer intermediate layer having excellent oxygen permeability is used. This multi-layer film is used as a bag after being heat-sealed.

[0005]

[Problems to be Solved by the Invention] A bag in which an ethylene vinyl alcohol copolymer is used as an intermediate layer and a heat-sealing resin is laminated on both sides of the bag is used for storing contents due to the excellent gas permeation resistance of the copolymer. Although it has excellent properties, it is still unsatisfactory as a bag for a bag-in-box in the combination of heat resistance and heat seal strength.

That is, in most cases, the bag-in-box is shipped with a liquid content weighing several kg to several tens of kg filled from the viewpoint of reducing the distribution cost. Large gravity acts on the seal portion, especially the seal portion at the bottom, and there is a problem of bag breakage due to impact due to drop or vibration during transportation.

For small packaging containers such as cans, bottles, and pouches, the hot filling method of contents is widely used from the viewpoint of improving the storability of the contents. There is a strong demand for improving the storability of the contents by filling the space. However, in this case, the heat resistance of the heat-sealed portion of the bag still has a problem to be solved.

The ethylene-vinyl alcohol copolymer has mechanical characteristics such as high rigidity but low elasticity as compared with the olefin resin used for heat sealing, and has low thermal conductivity, and is a heat insulating material for heat sealing. There is a problem that it works. Therefore, at the time of heat sealing, the heat sealing resin layer on the side in contact with the heat sealing bar becomes considerably high temperature, while the heat sealing resin layer on the side opposite to the heat sealing bar is still relatively low temperature and heat sealing is performed. It will be. This tendency is remarkable because the thickness of the multilayer film becomes large in a bag for box for filling heavy objects.

For this reason, as the heat-sealing resin, a resin having a relatively low heat-sealing temperature and a temperature range as wide as possible is used for bag making by heat-sealing. Since the temperature of the layer is too high, the mechanical strength of the edge of the heat-sealed portion, in particular, the drop impact strength is weakened, and so-called edge breakage or the like occurs when dropped.

Even if the sealing strength of the heat-sealing portion is satisfactory at room temperature, when the bag-in-box bag is hot-filled as described above, the heat-sealing portion retreats, that is, the sealing portion. It is still unsatisfactory in terms of heat resistance such as peeling.

Therefore, an object of the present invention is that the heat-sealing property at the time of bag making is excellent, and the heat-sealing part formed has both mechanical strength and impact resistance and heat resistance to withstand hot filling and the like. The present invention provides a bag-in-box and a bag used therein.

Another object of the present invention is to provide excellent heat sealability and impact resistance of the heat seal portion while having a laminated structure in which an ethylene vinyl alcohol copolymer is used as an intermediate layer and an olefin resin as inner and outer layers. A bag-in-box bag having a combination of heat resistance is provided.

[0013]

According to the present invention, there is provided a paper box and a resin film bag housed in the box, the bag comprising an olefin resin inner / outer layer and an ethylene vinyl alcohol copolymer. A linear ultra-low density having a density of 0.915 g / cm ³ or less and a melting point of 110 ° C. or more, which is formed by heat-sealing a laminated film including an intermediate layer A bag-in-box is provided, which is characterized in that it comprises a layer containing polyethylene.

According to the present invention, a laminated film comprising a paper box and a resin film bag housed in the box, the bag comprising an olefin resin inner / outer layer and an ethylene vinyl alcohol copolymer intermediate layer Of the inner and outer layers, at least the layer to be heat sealed has a density of 0.915.
g / cm ³ linear ultra low density polyethylene and the density of the melting point of more than 110 ° C. or less is 0.915 g / cm ³ or more linear low density polyethylene and the 25:75 to 95: resin composition containing 5 weight A bag-in-box is provided.

According to the present invention, a laminated film comprising an olefin resin inner / outer layer and an ethylene vinyl alcohol copolymer intermediate layer is heat-sealed to form a bag, and the inner / outer layer has a density of 0.915 g / cm ³ or less. And a layer containing a linear ultra-low density polyethylene having a melting point of 110 ° C. or higher, the bag being in an empty bag state, the first side piece and the second side piece, and the first side piece and the second side piece, respectively. The bag is composed of a third side piece and a fourth side piece that are folded inward from the edge of the second side piece into two pieces and a small space is formed between the bent portions. A first heat-sealing portion formed between the first side piece and the second side piece at the central portion of the end portion and a first side piece, a third side piece, and a third side piece that are continuous with the first heat sealing portion. All four side pieces and the second side piece have Back-in-box for a bag which is characterized in Rukoto.

[0016]

The function of the bag for the box of the present invention is as follows.
A laminated film comprising an olefin resin inner and outer layer and an ethylene vinyl alcohol copolymer intermediate layer is formed by heat-sealing, and the layer to be the heat-sealing layer has a density of 0.915 g / cm ³ or less, particularly 0.912
A remarkable feature is that the layer contains linear ultra-low density polyethylene having a melting point of 110 ° C. or higher at g / cm ³ or lower.

The linear ultra-low density polyethylene used in the present invention is composed of an ethylene-α olefin copolymer, and is a linear low-density polyethylene (LLDPE) or ethylene-α olefin.
It is similar to the olefin copolymer elastomer, linear low density polyethylene is generally 0.920 g / cm ³ or more, in particular that it has a lower density than whereas with a 0.925 g / cm ³ or more density, And the ethylene-α-olefin copolymer elastomer has a density of generally 0.900.
It is less than g / cm ³ and amorphous, and has no clear crystalline melting peak in differential scanning calorimetry (DSC), whereas linear ultra-low density polyethylene is still crystalline and has a clear crystalline melting. They differ in that they show peaks. Although there is no strict definition of the density, those having a density of 0.915 g / cm ³ or less are generally called ultra-low density.

Conventionally, linear low density polyethylene (LLDP
E) is often used as a heat-sealing material for a multilayer film for heat-sealing because it has excellent mechanical properties, particularly toughness, among polyethylenes, and has good pinhole resistance. This is because the heat-sealing conditions are not narrow, but when it is combined with an ethylene vinyl alcohol copolymer to form a bag for a bag-in-box, it may be dropped and
Edge cutting, bottom cutting, etc. occur, and application to this application has not yet succeeded.

On the other hand, when the ethylene-α-olefin copolymer elastomer is used for the purpose of modifying the linear low density polyethylene, it should be satisfactory in terms of strength against drop impact, but the heat resistance of the heat-sealed portion is high. Poorly, in the case of the hot filling described above, peeling or receding of the seal portion occurs, and a problem still remains in terms of sealing reliability. Further, a bag using a large amount of this elastomer is not stiff, and in this respect as well, it is inferior in commercial value to a bag using an ordinary olefin resin.

On the other hand, according to the present invention, when linear ultra-low density polyethylene is selected as the heat-sealable resin for the ethylene vinyl alcohol copolymer intermediate layer and is used as a bag for a bag-in-box, It has been found that the heat-sealing property at the time is excellent, and the heat-sealing portion formed has both mechanical strength and impact resistance and heat resistance to withstand hot filling and the like.

In the present invention, the fact that the above-mentioned advantages are achieved by using linear ultra-low density polyethylene has been found out from a large number of experimental results, and there are many unclear points, but the following is obtained. Thought to be a thing. The linear ultra-low density polyethylene used in the present invention is a copolymer of ethylene and α-olefin like a normal linear low-density polyethylene, and has a substantially linear polymer structure, It is crystalline, albeit somewhat low. It is considered that this crystallinity imparts heat resistance to the formed heat-sealed portion. In addition, this linear ultra low density polyethylene
Compared to ordinary linear low-density polyethylene, the comonomer segment has more structure, and the sequence seems to be random. This randomness seems to be the reason why the heat-sealing conditions can be broadened to provide excellent heat-sealing property and the impact resistance of the heat-sealed portion can be improved.

It has been found that the bag of the multilayer film having the linear ultra-low density polyethylene on the outer surface used in the present invention has other advantages in addition to the characteristics of the heat seal part. That is, this bag is superior in pinhole resistance to a bag having a normal linear low density polyethylene as the outer surface layer, and shows about twice the resistance. It can be said that this is an increase in resistance to vibration and shaking during transportation, and it is understood that the bag-in-box of the present invention can be used for long-distance transportation.

In the present invention, the linear ultra-low density polyethylene may be used alone or in combination with another resin in a content of 25% by weight or more. Especially with this linear ultra low density polyethylene, the density is 0.915 g /
25 cm ³ of normal linear low-density polyethylene:
It is preferable to combine them in a weight ratio of 75 to 95: 5 and use them as a resin composition. If the linear ultra-low density polyethylene is at least the above amount ratio, the heat sealability and the mechanical strength and impact resistance of the heat seal part and further the heat resistance are sufficiently improved, while the ordinary linear low density polyethylene is used. By containing the above amount in the above amount or more, the bag can be provided with necessary slipperiness and can be made to have a waist.

[0024]

Preferred Embodiment of the Invention

(Laminate Film) In “FIG. 1” showing an example of the laminate of the present invention, the laminate film 1 includes an intermediate layer 2 mainly composed of an ethylene vinyl alcohol copolymer and adhesive resin layers 2a and 2b. The surface olefin resin layers 3 and 4 are laminated on each other. At least one of the surface olefin resin layers 3 and 4 to be heat-sealed, preferably both layers are layers containing a linear ultra-low density polyethylene.

I. Ethylene Vinyl Alcohol Copolymer In the present invention, the ethylene vinyl alcohol copolymer is used as a gas barrier resin because it has an excellent oxygen permeability coefficient and can be thermoformed. As the ethylene vinyl alcohol copolymer, for example, an ethylene-vinyl acetate copolymer having an ethylene content of 20 to 60 mol%, particularly 25 to 50 mol%,
A saponified copolymer obtained by saponification so that the saponification degree is 96 mol% or more, particularly 99 mol% or more is used. The ethylene vinyl alcohol copolymer should have a molecular weight sufficient to form a film, and is generally 0.01 dl /% as measured at 30 ° C. in a mixed solvent of 85:15 by weight of phenol: water. g or more, especially 0.0
It is desirable to have a viscosity of 5 dl / g or more.

As the intermediate layer, it is preferable to use the ethylene vinyl alcohol copolymer alone, but other resins such as various olefin resins and polyamides, within the range not impairing the essence thereof, for example, generally 30% by weight or less.
Polyester and acid-modified olefin resin may be blended and used.

II. Linear Ultra Low Density Polyethylene As the linear ultra low density polyethylene forming the heat seal layer in the present invention, it is important to use one having the above-mentioned density and melting point. That is, a linear low density polyethylene having a density exceeding the range of the present invention is
If this product is used, as already pointed out, the heat-sealing property of the multilayer film when used as a bag-in-box deteriorates, and the impact resistance of the heat-sealing part is unsatisfactory. There is a tendency for breakage to occur easily. Further, if the melting point is below the range of the present invention, the heat resistance of the heat-sealed portion becomes unsatisfactory with respect to hot filling.

The linear ultra-low density polyethylene used in the present invention is a copolymer of ethylene and α-olefin,
Although composed of substantially linear polymer chains, the polymers have short branched chains based on α-olefins. This branched chain suppresses the crystallization of polyethylene, and the density is suppressed within the above low range. Generally, the crystallinity by X-ray diffraction is preferably 20 to 55%, more preferably 25.
Linear ultra-low density polyethylene in the range of 50% to 50% is used.

The α-olefin copolymerized with ethylene in the linear ultra-low density polyethylene is generally an α-olefin having 4 to 10 carbon atoms, particularly 4 to 8 carbon atoms, specifically 1-butene, 1 -Pentene, 1-hexene, 4-
It is methyl-1-pentene, 1-octene, 1-decene or a mixture thereof, with 1-butene, 1-hexene and 1-octene being particularly preferred. These α-olefins are used in an amount of 10 to 25% by weight, especially 1% by weight, of the copolymer.
It is preferably copolymerized in an amount of 2 to 20% by weight.

The linear ultra-low density polyethylene is 0.1 to 50 g / 10 in terms of processability into a multilayer film.
It is preferable to have a melt index of min, preferably 30 g / 10 min or less. If the melt index is less than 0.1 g / 10 min, the fluidity and dispersibility will be poor and the film formability will be reduced. On the other hand, when it exceeds 50 g / 10 min, the mechanical strength is lowered, so that the strength as a bag for box tends to be lowered.

III. Blended product In the present invention, if the linear ultra-low density polyethylene is contained in the heat-sealing resin layer in an amount of at least 25% by weight, particularly 30% by weight or more, the intended purpose of the present invention can be achieved. As the resin used in combination with the linear ultra-low density polyethylene, other olefin resins such as low density, medium density or high density polyethylene,
Olefinic resins such as linear low density polyethylene, crystalline polypropylene, ethylene-propylene copolymer, ethylene-propylene-butene-copolymer, ionomer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer Can be mentioned.

In a preferred embodiment of the present invention, the linear ultra-low density polyethylene (A) and the linear low-density polyethylene (B) having a density of 0.915 g / cm ³ or more are used at 25: 75-9.
A resin composition containing a weight ratio of 5: 5, especially 30:70 to 90:10, is used as the heat seal resin layer. That is, the linear low-density polyethylene has better compatibility with the above-mentioned linear ultra-low-density polyethylene than other olefin resins, and the mechanical strength of the multilayer film, especially the tensile strength, the tear strength, the toughness, etc. Is a preferable component for improving the strength and imparting the waist strength to the multilayer film.

In this resin composition, if the amount of linear low-density polyethylene used is less than the above range, the above properties are not sufficiently improved, while if it exceeds the above range, the object of the present invention is sufficient. Tend not to be achieved.

The linear low-density polyethylene (B) used in the present invention is also the same as the linear ultra-low density polyethylene (A).
Although it is a copolymer of ethylene and α-olefin, they are different in density. The crystallinity by X-ray diffraction is also different, and the crystallinity is generally 56.
Within the range of 80% to 80%.

In this linear low-density polyethylene (B), the α-olefin copolymerized with ethylene may be the one described above for the linear ultra-low density polyethylene, specifically, having 3 to 10 carbon atoms, particularly 4 to 8 α-olefins, preferably 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-
Decene or a mixture thereof, particularly 1-butene, 1-hexene and 1-octene are preferable. These α-olefins are preferably copolymerized in an amount of 3 to 15% by weight, particularly 3 to 10% by weight, based on the copolymer.

When the amount of the linear ultra-low density polyethylene is less than the above range, the heat sealability, the mechanical strength of the heat seal portion, the impact resistance and the heat resistance are not sufficiently improved, while the ordinary wire When the amount of low density polyethylene is less than the above range, slipperiness as a bag,
It also tends to lack strength in the waist.

The resin or resin composition used for forming the inner and outer layers in the present invention includes a compounding agent known per se, such as a lubricant,
One or more kinds of stabilizers, antioxidants, ultraviolet absorbers, antiblocking agents, colorants and the like can be blended according to a known formulation.

IV. Adhesive layer If there is no adhesiveness between the ethylene vinyl alcohol copolymer intermediate layer and the inner and outer surface layers, between the two resin layers,
Acid-modified olefin resins such as maleic anhydride, acrylic acid, methacrylic acid, itaconic anhydride, and the like, which are graft-modified with ethylenically unsaturated carboxylic acids or their anhydrides, low-, medium-, high-, or linear low- Density polyethylene,
It is preferable to interpose an adhesive layer such as polypropylene. Instead of interposing this adhesive layer, the above-mentioned resin can be contained in at least one of the intermediate layer and the inner and outer surface layers.

The laminated film or sheet used in the bag of the present invention is produced by melt-kneading the above-mentioned resins in a corresponding extruder, and extruding the melts simultaneously through a multilayer multi-die. A T-die method or an inflation film forming method is used for film formation, and the film or sheet may be unstretched or uniaxially or biaxially stretched.

The thickness of the ethylene vinyl alcohol copolymer layer in the laminated film is generally 2 to 30 μm,
It is particularly preferable that the thickness is in the range of 4 to 15 μm, and the thickness of the linear ultra-low density polyethylene-containing resin layer that becomes the heat seal layer is 30 to 150 μm, and particularly 50 to 120 μm.
The total thickness is 70 to 220μ.
m, particularly in the range of 100 to 300 μm.
It is preferable that the inner and outer surface layers are both linear ultra-low density polyethylene-containing resin layers having the same thickness. Further, this laminated film or sheet may be provided with scrap resin or the like as a layer between the intermediate layer and the inner and outer surface layers.

(Bag) The bag of the present invention can be produced by stacking two pieces of the above-mentioned multilayer film or sheet and heat-sealing the side edge portions thereof. A nozzle with a cap for filling and pouring the contents can be provided by heat sealing or the like in a portion near one side edge portion of one film or sheet.

A preferred bag of the present invention is, in an empty bag state, a first side piece and a second side piece, and two pieces inward from the edges of the first side piece and the second side piece, respectively. The bag is composed of a third side piece and a fourth side piece that are folded into a piece and have a small gap formed between the bent portions. The first heat seal formed between the second side piece and the continuous first and second side pieces, and further all of the fourth side piece and the second side piece are formed as a whole. And a second heat-sealed portion formed over.

In FIG. 2 (perspective view) and FIG. 3 (side view) showing a preferred example of the bag-in-box of the present invention, this is used for filling a carton box 10 and the contents contained therein. It consists of a bag 20. The carton box 10 has a rectangular parallelepiped shape, and includes four side walls 11, a bottom 12 and an openable lid 13. The content filling bag 20 includes a bag body 21 and
It comprises a mouth portion 22 for filling and unloading contents, and a cap 23 which is provided on the mouth portion 22 so as to be sealed and removable.

The bag body 21 is formed of the above-mentioned multi-layered plastic film or sheet, and has a shape and dimensions that fit snugly inside the carton box 10 when the contents are filled.

In FIG. 4 (perspective view) and FIG. 5 (cross-sectional view) showing the bag body in an empty bag state, this bag body 21
Consists of a first side piece 24 and a second side piece 25, and a third side piece 27 and a fourth side piece 28 folded inwardly from the edge 26 of these side pieces into two pieces. Made of A bent portion 29 is present between the third side piece 27 and the fourth side piece 28, and a small space is formed between the bent portions 29, 29 facing each other.

The bag body 21 may be a tubular body having no side seams, or a single film may be folded,
It may have one side seam overlap-sealed at the side edges, but preferably two films or sheets are superposed and two side seams 30a overlap-sealed at both edges, Those having 30b are preferable.

This bag body is heat-sealed at the top and bottom of the above-mentioned folded structure to form an upper heat-sealing portion 31 and a bottom heat-sealing portion 32. In the content-filled state, the content-filling bag 21 spreads in a rectangular parallelepiped shape, fits nicely into a rectangular parallelepiped carton box, and eliminates a gap. Therefore, damage or damage caused by misalignment between the bag and the box during transportation, etc. This has the advantage that the occurrence of pinholes is prevented.

The most vulnerable part of the bag to drop impact is the heat-sealed part at the bottom, especially the part where both sides are folded inward and the inner bent edges are heat-sealed. When a drop impact is applied in the state of being filled with, the tensile stress is locally concentrated in the part,
Occurrence of cracks and pinholes, damage to the heat seal, and problems such as leakage occur.However, according to the present invention, the heat seal portion is made of the linear ultra-low density polyethylene-containing resin described above, and therefore the drop impact It is possible to prevent the local bag from being broken at the bottom due to such reasons. In particular, the effect tends to become more remarkable as the inner volume of the bag-in-box increases. When the capacity coefficient (g / cm) is defined as the ratio of the actual internal capacity (g) of water converted to water and the total heat-sealing length (cm), drop impact resistance is required when this value is 10 or more, especially 20 or more. A remarkable effect on the heat resistance was observed, and the same tendency was observed for the retreat and breakage of the heat-sealed portion during hot filling with water or the like. It is considered that as the capacity coefficient increases, the stress due to the shock wave applied to the vicinity of the seal portion dramatically increases when dropped, and the creep force applied to the seal portion significantly increases in heat resistance.

In the bag making of the bag of the present invention, it is a remarkable advantage that heat sealing can be carried out under a considerably wide range of conditions, but it is generally 180 to 270 ° C., particularly 210 to 2
Preference is given to carrying out at a temperature of 50 ° C. It is also an advantage of the present invention that heat sealing can be performed using a heat sealing bar having a temperature difference between the front and back. Of course, heat seal,
It can also be performed by ultrasonic heat sealing, dielectric heat sealing, laser heat sealing, or the like.

[0050]

EXAMPLES The present invention will be specifically described in the following examples. Example 1 An ethylene / butene-1 copolymer (LLD) was added to the extruder for the outer layer.
PE-, density 0.905 g / cm ³ , melting point 120 ° C.,
MFR 0.5g / 10min) and ethylene butene-
1 copolymer (LLDPE-, density 0.920 g / cm
³ , a melting point of 121 ° C., MFR 0.8 g / 10 min) and a blend of 70:30 by weight were mixed in an extruder for the intermediate layer with a saponified ethylene vinyl acetate copolymer (ethylene content 40 mol%, saponification degree). 99%) by an extruder for adhesive layer, based on an ethylene-based copolymer, maleic anhydride graft-modified resin (density 0.920, melting point 104 ° C, M
FR1.3 g / 10 min) respectively, coextruded using a multi-layer inflation die and air-cooled to obtain an inner layer (I) / adhesive layer (I) / intermediate layer / adhesive layer (II) / outer layer (II). = 82/4/8/4/82 (μm)
A three-kind five-layer film having a total film thickness of 180 μm was formed (used in the present invention 1). For comparison, LLDPE-alone (comparative example 1) was used as the resin for the inner and outer layers, and LLDPE-
For 70 parts, ethylene-based elastomer (density 0.8
85 g / cm ³ , melting point cannot be measured, softening point is 65 ° C, M
A film having the same film thickness constitution was prepared by the same method for a blend of 30 parts of FR 3 g / 10 min) (Comparative Example 2).

Then, for these films, the width 57
2 pieces of cm are used, after the upper film is perforated, a filling nozzle is attached, then folded in a gusset shape and heat-sealed on both side edges, and further heat-sealed the top and bottom parts. , Width 41 cm in flat dimension, length 57
A gusset bag for an internal volume of 20 cm (actual internal volume: 20.45 liter, volume coefficient: 72) was produced. Here, a hot plate seal having a seal width of 10 mm was used for heat sealing. As a condition, the upper set temperature is a)
210 ℃, b) 230 ℃, c) 250 ℃, the bottom is all 7
Performed at 0 ° C., surface pressure of 5.2 kg / cm ² , time of 1.5 seconds,
Cooling was at room temperature, surface pressure of 4.5 kg / cm ² , and time of 1.5 seconds.

The container performance described below was evaluated for the bags thus produced. As heat resistance of the bag, hot water of 90 ° C. was filled in each 20 liter bag, and then the gusset bag was left standing for about 1 hour, and the presence or absence of retreat of the seal portion and the presence or absence of leakage were inspected. Table 1 shows the number of leaks out of 10 bags under each condition, or the average value of the maximum seal retreat width (mm) in the case of no leak.
Shows the evaluation results of the heat resistance of the bag. On the other hand, as the drop impact resistance of the bag, each 20 liter bag was filled with 5 ° C. water, and then stored in a dedicated corrugated carton with an outer width of 32 cm, a length of 29 cm, and a height of 30 cm, and stored at 5 ° C. for 48 hours.
About what was stored for a time, it dropped from a height of 90 cm so that the bottom of the carton was horizontal to the concrete surface, and the occurrence of leakage was examined. Table 1 shows the number of leaked bags in the test of 10 bags under each condition.

As a result, in the bag in which the outer layer resin is made of LLDPE-alone, heat-resistant heat-sealing can be obtained at a high heat-sealing temperature, but at any heat-sealing temperature, there are many leaks due to dropping, and particularly high-temperature heat-sealing. All the seals leaked and there were no good conditions (Comparative Example 1). In addition, drop impact resistance is significantly improved by adding a soft elastomer to LLDPE-
There is no heat-sealing condition with which sufficient heat resistance can be obtained, and leakage or seal receding is remarkable under any condition (Comparative Example 2). On the other hand, the so-called ultra-low density LLDP of the present invention 1 is used.
When E- was used as the main component of the outer layer resin, stable bag performance satisfying both heat resistance and drop impact resistance could be achieved under a wide range of heat sealing conditions.

[0054]

[Table 1]

Example 2 As an outer layer resin, as shown in Table 2, the LLD of the present invention 1 was used.
The composition ratios of PE- and-were changed, a multilayer film having the same structure as in Example 1 was formed into a bag, and various container performances were evaluated (Comparative Examples 3 and 4). The present invention 2 to 5). Further, after fixing the compounding ratio of LLDPE- to 50 parts by weight, the same evaluation was performed in the case of blending 50 parts of ethylene / α-olefin copolymer having various melting points and densities as shown below. .. As ethylene / α-olefin copolymers having various melting points, three kinds of ethylene / hexene-1 copolymers (LLDPE-: density 0.900 g / cm ³ , melting point 1
03 ℃, MFR 0.8g / 10min, LLDPE-
: Density 0.900 g / cm ³ , melting point 110 ° C., MFR
0.7g / 10min, LLDPE-: Density 0.9
00 g / cm ³ , melting point 123 ° C., MFR 0.8 g / 1
0 min) was used in Comparative Example 5 and Inventions 6 and 7, respectively. In addition to ethylene / α-olefin copolymers having various densities, ethylene / butene-
1 copolymer (LLDPE-: density 0.910, melting point 1
21 ° C, MFR 0.6g / 10min), ethylene
Octene-1 copolymer (LLDPE-: density 0.91
5, melting point 122 ° C., MFR 0.7 g / 10 min),
Ethylene-4-methylpentene-1 copolymer (LLDP
E-: Density 0.918, melting point 123 ° C, MFR 0.
8 g / 10 min) according to the present invention 8 and 9, comparative example 6
Used in.

As a result, so-called ultra-low density LLDPE
When the composition ratio of-is changed, the composition ratio is 25 wt%
Below (Comparative Examples 3 and 4), the drop impact resistance is remarkably lowered, and a higher heat-sealing temperature tends to be required to secure the heat resistance of the heat-sealing. , It was difficult to find the conditions to secure the performance of both sides. When most of the composition is composed of ultra-low density LLDPE (Inventions 4 and 5), sufficient bag performance was obtained, but the film was weak and slippery. Due to shortage or large elongation at high temperature, in gusset folding bag,
The range of manufacturing conditions was narrow, such as poor folding and the tendency for the heat-sealed portion to stretch. Further, when the contents are filled and then stored in a corrugated cardboard box, the slippage with the inner surface of the carton tends to be poor and the workability tends to be poor. The blending ratio of the ultra-low density resin is preferably 25 wt% or more, and when workability and the like are taken into consideration, 50 wt% or more and less than 90 wt% is a more suitable range.

If the melting point of the ultra-low density resin used in the blending is too low, the heat resistance of the heat seal tends to be impaired, and if it is 105 ° C. or higher, the hot filling temperature 85 to 85 used in ordinary juices and the like is used. When it withstands 95 ° C and the density exceeds 0.915 g / cm ³ (Comparative Example 5)
Loses its flexibility, which reduces drop impact resistance.
The frequency of leakage due to falling tended to increase.

[0058]

[Table 2]

Example 3 With respect to the films used in the present invention 1 and the comparative example 1 of Example 1, respectively, the contents shown in Table 3 were 10 liters and 20 liters, respectively.
1 liter and 30 liter pillow type bags
A bag was made from a sheet of film in the order of filling nozzle perforation, nozzle adhesion, backing seal (width 10 mm, 230 ° C.), and both ends seal (the same). The capacity coefficients represented by the ratio of the total heat-sealing length (cm) to the actual internal capacity (g) of these bags were 81, 130 and 172 for the bags of each size, respectively.

After filling these bags with juice heated to 90 ° C., the bag was allowed to cool at room temperature as it was, and after about 6 hours, it was inspected whether the seal retreated or leaked. Further, these bags were stored in a cardboard box of a predetermined size and stored at 5 ° C for 48 hours. After dropping horizontally from the height of 90 cm so that the part with the backing on the concrete surface was below, there was no leakage. The occurrence was investigated. Table 3 shows the results of performing these tests with 10 bags under each condition.

According to this, the outer layer resin is very common L
In the case of LDPD-single unit, as the internal capacity becomes larger and the capacity coefficient becomes larger, receding of the seal part and occurrence of leakage increase, and leakage at the time of dropping (mainly cutting near the seal part) ) The frequency tended to be high (Comparative Example 7), and the difference from the case of using the ultra-low density LLDPE of the present invention 10 as the main component was further clarified. It is considered that the larger the volume is, the more the stress applied to the seal portion is increased, and the stronger the shock wave at the time of dropping is. Therefore, the bag-in-box of the present invention is more effective in a bag having a large volume. It is understood to work.

[0062]

[Table 3]

[0063]

According to the present invention, a paper box and a resin film bag housed in the box are provided.
In the bag-in-box wherein the bag is formed by heat-sealing a laminated film comprising an olefin resin inner / outer layer and an ethylene vinyl alcohol copolymer intermediate layer, at least the inner / outer layer is heat-sealed as a layer. A density of 0.915 g / cm ³ or less and a melting point of 1
By using the layer containing the linear ultra-low density polyethylene of 10 ° C. or higher, excellent heat sealability and a combination of impact resistance and heat resistance of the heat seal portion were obtained.

A bag provided with a folding seal portion
Also in the bag for filling the contents for the in-box, by forming the heat seal part with the linear ultra-low density polyethylene, even if the tensile stress due to a drop impact is concentrated on the folding seal part, the bag may be broken or damaged. Edge break is prevented,
It was possible to effectively prevent the bag from breaking and leaking. Further, the contents were hot-filled, and in combination with the fact that the intermediate layer was composed of an ethylene vinyl alcohol copolymer, the storability of the contents could be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a laminate of the present invention.

FIG. 2 is a perspective view of a preferred example of the bag-in-box of the present invention.

FIG. 3 is a side view of the bag-in-box of FIG.

FIG. 4 is a perspective view showing an example of a bag for filling contents.

FIG. 5 is a cross-sectional view of an example of a bag for filling contents.

[Explanation of symbols]

1 is a laminate film, 2 is an intermediate layer mainly composed of ethylene vinyl alcohol copolymer, 2a and 2b are adhesive resin layers, 3 and 4 are surface olefin resin layers containing linear ultra-low density polyethylene, and 10 is Carton box, 20 is a bag, 21 is a bag body, 24 is a first side piece, 25 is a second side piece, 26 is their edges, 27 is a third side piece, 2
8 is a fourth side piece, 29 is a bent portion, and 32 is a bottom seal portion.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroaki Niwa 2-4-8 Terao Nishi, Ayase City, Kanagawa Prefecture Fujimi Dormitory

Claims (3)

[Claims] 1. A heat-sealing laminated film comprising a paper box and a resin film bag housed in the box, the bag comprising a olefin resin inner / outer layer and an ethylene vinyl alcohol copolymer intermediate layer. A layer formed of a bag, wherein at least the inner and outer layers to be heat-sealed are layers containing a linear ultra-low density polyethylene having a density of 0.915 g / cm ³ or less and a melting point of 110 ° C. or more. Bag-in-box to do. 2. A heat-sealing laminated film comprising a paper box and a resin film bag accommodated in the box, the bag comprising an olefin resin inner / outer layer and an ethylene vinyl alcohol copolymer intermediate layer. at least heat-sealed by the layer density of 0.915 g / cm ³ linear ultra low density polyethylene and a density of more than 110 ° C. melting point or less of the bag and the inner and outer layers are formed by the 0.915 g / cm ³ or more A bag-in-box, which is formed from a resin composition containing the linear low-density polyethylene of 1. in a weight ratio of 25:75 to 95: 5. 3. A bag formed by heat-sealing a laminated film comprising an olefin resin inner / outer layer and an ethylene vinyl alcohol copolymer intermediate layer, wherein the inner / outer layer has a density of 0.915 g / cm ³ or less and a melting point of 110 ° C. The bag is formed of a layer containing the above linear ultra-low density polyethylene, and the bag is in an empty bag state, the first side piece and the second side piece, and the first side piece and the second side piece, respectively. The bag is composed of a third side piece and a fourth side piece that are folded inward from the edge of the bag in two pieces and a small space is formed between the bent portions, and the bag has a central portion at the upper and lower ends. In the first heat-sealing portion formed between the first side piece and the second side piece, and in succession thereto, the first side piece and the third side piece and further the fourth side piece. All of the second side pieces have a second heat-sealing section made throughout. Click-in-box for the bag.