CN104608988B - Pulling-on piece and the packing container containing the pulling-on piece - Google Patents

Abstract

The invention relates to a pull-tab for a packaging container, the pull-tab comprising layers in the following order: an aluminum foil layer, an MPE/LDPE/LLDPE mixture layer for a packaging container, the invention also relates to a packaging container comprising a main body of the packaging container comprising a The opening at the top of the container for pouring food is covered by a pull-tab and sealed from above the pull-tab along the periphery of the opening, the opening is covered by an inner band from below, the lower surface of the periphery of the opening and The inner surfaces of the pull tabs are welded and bonded to each other. The pull tab has a good opening effect.

Description

Pull-tab and packaging container containing the pull-tab

technical field

The present invention relates to a handle for a packaging container, and also relates to a method for manufacturing the handle and a packaging container using the handle.

Background technique

A packaging container for food has a packaging container body, an opening provided at the top of the container for pouring out the food, opening means such as a spout, lid or cap, and a pull tab or straw. FIG. 2 shows an example of a packaging container sealed with a pull tab 4 . The packaging container 1 has a main body 2 and an opening 3 for food provided at the top of the container.

FIG. 1 is a cross-sectional view showing an opening and a portion around the opening. In order to seal the opening 3 , the opening 3 is covered with the handle 4 and sealed along the outer periphery 3 a of the opening 3 from above the handle 4 . In addition, the opening 3 is covered with the inner tape 5 from below, and the lower surface of the outer periphery 3a of the opening 3 and the inner surface of the pull tab 4 are welded and bonded to each other so as to be sealed.

In order to pour out the food, the unsealed part of the pull tab 4 is pulled up, and the inner band 5 is broken near the edge portion of the opening to tear the pull tab 4 and break the seal of the opening 3 . In the above process, it is very important whether the packaging container is easy to tear, that is, when peeling off the pull tab, it is necessary to obtain a good opening effect, and the tear that is not neat and has fiber falling will contaminate the food.

Contents of the invention

One aspect of the present invention provides a pull-tab comprising at least layers in the following order: an aluminum foil layer, an MPE/LDPE/LLDPE blend layer.

The mass of the MPE accounts for 20-50% of the MPE/LDPE/LLDPE mixture layer.

The pull-tab also includes an LDPE/LLDPE mixture layer, and the LDPE/LLDPE mixture layer is arranged between the aluminum foil layer and the MPE/LDPE/LLDPE mixture layer.

The pull-tab also includes an LLDPE layer, which is arranged between the aluminum foil layer and the MPE/LDPE/LLDPE mixture layer.

The pull-tab also includes an LLDPE layer, which is arranged between the aluminum foil layer and the LDPE/LLDPE mixture layer.

The weight ratio of LLDPE in the MPE/LDPE/LLDPE mixture layer is greater than the weight ratio of LLDPE in the LDPE/LLDPE mixture layer.

Another aspect of the present application relates to a method of manufacturing a pull tab, comprising the steps of:

Coextrude the following components in the order described below: Al foil layer, MPE/LDPE/LLDPE blend layer; or Al foil layer, LDPE/LLDPE blend layer, MPE/LDPE/LLDPE blend layer; or Al foil layer, LLDPE layer, MPE/ LDPE/LLDPE mixture layer, or aluminum foil layer, LLDPE layer, LDPE/LLDPE mixture layer, MPE/LDPE/LLDPE mixture layer, and these layers are laminated in the above order. The raw materials used in the above method are all commonly used raw materials, without special requirements, and each step of lamination can be carried out under basically the same process conditions, and there are no special requirements for processing equipment. It can also be processed and prepared by blow molding.

Another aspect of the present application relates to a packaging container using the above-mentioned pull tab, the packaging container includes a packaging container main body, and the packaging container main body includes an opening portion provided on the top of the container for pouring out food, and the opening portion is closed. The pull-tab is covered and sealed from above the pull-tab along the outer periphery of the opening, the opening is covered by the inner tape from below, the lower surface of the outer periphery of the opening and the inner surface of the pull-tab are welded to each other, and the pull-tab includes the following sequence The layer: aluminum foil layer, MPE/LDPE/LLDPE mixture layer, the mass of the MPE accounts for 20-50% of the MPE/LDPE/LLDPE mixture layer.

These and other features, aspects and advantages of the present application will be better understood with reference to the following detailed description.

Description of drawings

FIG. 1 is a cross-sectional view showing an opening and its vicinity.

Fig. 2 is a perspective view showing an example of a packaging container.

Symbol Description

1 packaging container

2 The main body of the packaging container

3 opening

4 pull tabs

5 inner strap

3a Perimeter of the opening

detailed description

The present disclosure may be more readily understood by reference to the following detailed description of the preferred methods of practicing the invention, together with the included Examples. In the following specification and claims there will be reference to a number of terms which are defined to have the following meanings.

Singular forms include plural referents unless the context clearly dictates otherwise.

"Optional" or "optionally" means that the item or event described thereafter may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

Approximate terms in the specification and claims are used to modify the quantity, which means that the present invention is not limited to the specific quantity, but also includes acceptable modifications that are close to the quantity and will not cause changes in the relevant basic functions. Accordingly, a numerical value modified by "about", "about", etc., means that the present invention is not limited to the precise numerical value. In some instances, approximate terms may correspond to the precision of the instrument for measuring the value. Throughout the specification and claims of this application, range limitations may be combined and/or interchanged, unless otherwise stated such ranges include all subranges contained therebetween.

"Polymer blend" refers to a physical mixture of two or more homopolymers, copolymers or homopolymers and copolymers with different molecular structures. Generally, there is no covalent bond between the macromolecules of the two components. The mixing of polymers is an endothermic process and is a heterogeneous system in which one polymer is dispersed in another. The purpose of blending is to prepare polymer materials with improved or unique properties in certain properties. Polymer blends are the earliest heterogeneous polymers. As early as the beginning of the 20th century, there was a patent report on the preparation of impact-resistant polystyrene by blending. Blending is relatively simple in technology, and the selection range of components is large, and it can be easily made into new materials with special properties, so it develops rapidly.

The term "LDPE" used in this application refers to low density polyethylene, and the term "LLDPE" used in this application refers to linear low density polyethylene.

The term "MPE" used in this application refers to metallocene polyethylene, which is polyethylene synthesized with metallocene as a catalyst. Therefore, the performance is significantly different from that of PE polymerized by traditional Ziegler-Natta catalysts.

A pull tab, the pull tab includes layers in the following order: an aluminum foil layer, an MPE/LDPE/LLDPE mixture layer, and the mass of the MPE accounts for 20-50% of the MPE/LDPE/LLDPE mixture layer. Experiments have proved that 20-50% is a ratio with good opening effect. After LDPE and LLDPE are mixed, the mixture layer has general heat-sealing performance.

As a preferred technical solution, the pull tab further includes an LDPE/LLDPE mixture layer, and the LDPE/LLDPE mixture layer is arranged between the aluminum foil layer and the MPE/LDPE/LLDPE mixture layer. The LDPE/LLDPE mixture layer can be used as a buffer for the aluminum foil layer and the MPE/LDPE/LLDPE mixture layer, which can effectively improve the opening effect.

As a preferred technical solution, the pull tab further includes an LLDPE layer, which is arranged between the aluminum foil layer and the MPE/LDPE/LLDPE mixture layer. After adding the LLDPE layer, the opening effect is better and excellent, and several layers with the LLDPE concentration gradually decreasing from the inside to the outside are obtained, which improves the opening effect.

As a preferred technical solution, the pull tab further includes an LLDPE layer, which is arranged between the aluminum foil layer and the LDPE/LLDPE mixture layer.

As a preferred technical solution, the weight ratio of LLDPE in the MPE/LDPE/LLDPE mixture layer is greater than the weight ratio of LLDPE in the LDPE/LLDPE mixture layer. This scheme can obtain more excellent opening effect.

By adopting the above preferred technical solution, it can be proved through experiments that the preferred solution can obtain a pull tab with better breaking performance, and it is easier to obtain a neat and fiber-free fracture.

Prevent film peeling during the tearing process, film residue or stringing, and poor appearance of the peeled surface. Preferably, the adhesive resin suitable for the above conditions is a hyperbranched nano-modified polyurethane adhesive (CPUAD) with a specific structure, which is prepared by the following steps:

(1) Weigh the tribasic acid and dibasic alcohol into the reactor according to the acid-alcohol molar ratio 1: (1.0～1.2), raise the temperature to 140°C, add the catalyst accounting for 2‰ of the total mass of the reaction system, and put it under the condition of nitrogen protection Stir down;

The structure of the tribasic acid is as follows:

Described glycol is propylene glycol;

(2) When the fractional distillation temperature at the top of the tower is less than 80°C, start to gradually heat up to the reaction temperature of 210°C, and keep it warm for 2 to 3 hours under nitrogen protection;

(3) At a reaction temperature of 210°C, gradually vacuumize from low to high until the acid value of the product is less than 1mg KOH/g to obtain qualified polyester;

(4) Weigh the required number of parts of the vacuum dehydrated polyester into the reactor, and raise the temperature to 80°C;

(5) Add the required number of chain extenders after distillation and dehydration, and mix well;

(6) Add the required amount of isocyanate, stir rapidly, and gradually add the mixed solvent when the stirring is difficult;

(7) Add the required number of catalysts and stir for 1 hour at 60-80°C;

(8) Add the required number of dried nano-silica and silane coupling agent, and stir at 60-80°C for 1 hour;

(9) Add the required number of polymerization inhibitors and stir for 10 minutes;

(10) After inspection, put it into the rubber hose to make the finished product.

When the above-mentioned isocyanate is a solid aromatic isocyanate, it needs to be melted in hot water at 60-80°C before adding.

The adhesive is used to bond aluminum foil and resin, and achieve bonding by spraying or laminating.

For the pull tab-inner band opening structure, because there are at least 5 layers of structure in the inner band, and the pull tab also has a 2-layer structure, the bonding strength between each layer should be significantly greater than the breaking strength of the inner band. In another aspect of the applicant of the present invention In this patent, a brand-new inner belt structure is provided, and the inner belt has better fracture performance, so that the fracture is neat and free of fibers.

The structure of the pull tab can use an adhesive to bond the heat-sealing layer and the aluminum foil, but the adhesive may make the heat-sealing layer more likely to break, resulting in irregular breakage of the heat-sealing layer. The inventors of the present invention have found through a large number of experiments that the adhesive used to bond the heat-seal layer and the aluminum foil layer is not necessary. The present invention maintains the heat-sealing performance of the heat-seal layer by improving the tear strength of the heat-seal layer, that is, Pull tabs with neat breaks and no fibers can be obtained. Adopting the solution of the present invention breaks through the conventional thinking of those skilled in the art (that is, improving the opening effect by increasing the interlayer adhesion), and simply improving the tear strength of the heat-sealing layer can obtain a pull tab with a good opening effect.

Another aspect of the present application relates to a method of manufacturing a pull tab, comprising the steps of:

Coextrude the following components in the order described below: Al foil layer, MPE/LDPE/LLDPE blend layer; or Al foil layer, LDPE/LLDPE blend layer, MPE/LDPE/LLDPE blend layer; or Al foil layer, LLDPE layer, MPE/ LDPE/LLDPE mixture layer, or aluminum foil layer, LLDPE layer, LDPE/LLDPE mixture layer, MPE/LDPE/LLDPE mixture layer, and these layers are laminated in the above order. The raw materials used in the above method are all commonly used raw materials, without special requirements, and each step of lamination can be carried out under basically the same process conditions, and there are no special requirements for processing equipment. It can also be processed and prepared by blow molding.

Another aspect of the present application relates to a packaging container using the above inner tape.

The packaging container includes an opening arranged on the top of the container for pouring out food, the opening is covered by a pull-tab, and is sealed from above the pull-tab along the periphery of the opening, the opening is covered by an inner tape from below, and the opening The lower surface of the outer periphery of the part and the inner surface of the pull tab are welded and bonded to each other, and the pull tab includes layers in the following order: an aluminum foil layer, an MPE/LDPE/LLDPE mixture layer, and the mass of the MPE accounts for the MPE/LDPE/LLDPE mixture layer 20-50% of that.

In one embodiment, the LDPE in a layer such as an MPE/LDPE/LLDPE blend layer may be a homopolymer, but with the proviso that the homopolymer may optionally contain up to 5% of another alpha-olefin. LDPE is often referred to as a polyethylene homopolymer, although potentially small amounts of other alpha-olefins are present.

In one embodiment, the LDPE suitable for use in the present application may have the following density measured according to ASTM D1505: 0.910-0.925, preferably 0.918-0.925; the following melting point measured according to ASTM D3418: about 102°C to about 110°C, Optionally from about 102°C to about 106°C, or alternatively from about 106°C to about 110°C; and Vicat softening temperature according to ASTM D1525: from about 86°C to about 102°C, optionally from about 92°C to about 102°C.

In one embodiment, the density of LLDPE usable in this application is 0.918-0.930, preferably 0.919-0.925.

In one embodiment, an MPE suitable for use herein is a copolymer of ethylene with about 0.2 mole percent to about 0.5 mole percent 1-hexene. In embodiments, MPE suitable for use in the present application, such as MLLDPE, may have the following density, measured according to ASTM D1505: from about 0.913 g/cc to about 0.918 g/cc, optionally from about 0.913 g/cc to about 0.915 g/cc; or the following melting point as determined according to ASTM D3418: from about 112°C to about 120°C, alternatively from about 112°C to about 115°C, or alternatively from about 115°C to about 119°C; or according to ASTM The following melt index as determined by D1238: from about 0.7 g/10 min. to about 1.6 g/10 min., optionally from about 0.9 g/10 min. to about 1.3 g/10 min.; or Vicat softening according to ASTM D1525 Temperature: from about 100°C to about 106°C, alternatively from about 100°C to about 103°C, or alternatively from about 103°C to about 106°C.

The thickness of the aluminum foil of the pull tab can be selected from 5-100 microns, the LLDPE layer is 1-20 microns, the LDPE/LLDPE mixture layer is 1-12 microns, and the MPE/LDPE/LLDPE mixture layer is 8-20 microns. Lamination is carried out according to the above sequence to obtain a pull tab.

The present invention will be described in detail below with reference to several examples.

example 1

Pull tab:

Aluminum foil: Tianjin Dongyue, 40 microns.

MPE/LDPE/LLDPE mixture layer: MPE/LDPE/LLDPE=1:1:1.

LLDPE: melt index 2.0, density 0.918 g/cm3, MPE: melt index 1.0, density 0.918 g/cm3, LDPE: melt index 2.0, density 0.924 g/cm3, all of which are mass ratios.

The resins described above were heated and melted, and the layers of the molded multilayer film were 40 microns of aluminum foil and 25 microns of MPE/LDPE/LLDPE blend layer.

Inner strap:

The layers used to prepare the inner belt are: the outer layer of a blend of low-density polyethylene and linear low-density polyethylene in a weight ratio of 1/5, and the blend of low-density polyethylene and linear low-density polyethylene in a weight ratio of 5/1. An intermediate layer, an adhesive layer comprising an adhesive (Ad) and a barrier layer of ethylene-vinyl alcohol copolymer (EVOH).

Heating and melting the resin as described above, the molten resin is copolymerized according to LDPE and LLDPE blend/LDPE and LLDPE blend/adhesive/ethylene vinyl alcohol The sequence of material/adhesive layer/low density polyethylene and linear low density polyethylene blend/low density polyethylene and linear low density polyethylene blend is filled into a co-extrusion die and molded into a film . The molded multilayer film has the characteristics of LLDPE (layer thickness of 6 microns)/LDPE (layer thickness of 2 microns)/Ad (layer thickness of 5 microns)/EVOH (layer thickness of 7 microns)/Ad (layer thickness of 5 μm)/LDPE (layer thickness 9 μm)/LLDPE (layer thickness 6 μm).

Example 2

Pull tab:

Aluminum foil: Tianjin Dongyue, 40 microns.

MPE/LDPE/LLDPE mixture layer: MPE/LDPE/LLDPE=1:2:2.

LLDPE: melt index 2.0, density 0.918 g/cm3, MPE: melt index 1.0, density 0.918 g/cm3, LDPE: melt index 2.0, density 0.924 g/cm3, all of which are mass ratios.

The resins described above were heated and melted, and the layers of the molded multilayer film were 40 microns of aluminum foil and 25 microns of MPE/LDPE/LLDPE blend layer.

The inner band is the same as Example 1.

Example 3

Pull tab:

Aluminum foil: Tianjin Dongyue, 40 microns.

MPE/LDPE/LLDPE mixture layer: MPE/LDPE/LLDPE=4:3:3.

LLDPE: melt index 2.0, density 0.918 g/cm3, MPE: melt index 1.0, density 0.918 g/cm3, LDPE: melt index 2.0, density 0.924 g/cm3, all of which are mass ratios.

The resins described above were heated and melted, and the layers of the molded multilayer film were 40 microns of aluminum foil and 30 microns of MPE/LDPE/LLDPE blend layer.

The inner band is the same as Example 1.

Example 4

Pull tab:

Aluminum foil: Tianjin Dongyue, 40 microns.

LLDPE layer: melt index 2.0, density 0.918 g/cm3

MPE/LDPE/LLDPE mixture layer: MPE/LDPE/LLDPE=1:2:2.

LLDPE: melt index 2.0, density 0.918 g/cm3, MPE: melt index 1.0, density 0.918 g/cm3, LDPE: melt index 2.0, density 0.924 g/cm3, all of which are mass ratios.

The resins described above were heated and melted, and the layers of the molded multilayer film were 40 microns of aluminum foil, 15 microns of LLDPE layer and 15 microns of MPE/LDPE/LLDPE blend layer.

The inner band is the same as Example 1.

Example 5

Pull tab:

Aluminum foil: Tianjin Dongyue, 40 microns.

LDPE/LLDPE mixture layer: LDPE/LLDPE=1:1

MPE/LDPE/LLDPE mixture layer: MPE/LDPE/LLDPE=1:2:2.

LLDPE: melt index 2.0, density 0.918 g/cm3, MPE: melt index 1.0, density 0.918 g/cm3, LDPE: melt index 2.0, density 0.924 g/cm3, all of which are mass ratios.

The resins described above were heated and melted, and the layers of the molded multilayer film were 40 microns of aluminum foil, 15 microns of LLDPE layer, 10 microns of LDPE/LLDPE blend layer, and 10 microns of MPE/LDPE/LLDPE blend layer.

The inner band is the same as Example 1.

Example 6

Pull tab:

Aluminum foil: Tianjin Dongyue, 40 microns.

LLDPE layer: melt index 2.0, density 0.918 g/cm3

LDPE/LLDPE mixture layer: LDPE/LLDPE=1:3

MPE/LDPE/LLDPE mixture layer: MPE/LDPE/LLDPE=1:1:1.

LLDPE: melt index 2.0, density 0.918 g/cm3, MPE: melt index 1.0, density 0.918 g/cm3, LDPE: melt index 2.0, density 0.924 g/cm3, all of which are mass ratios.

By heating and melting the resins as described above, the layers of the molded multilayer film were 40 microns of aluminum foil, 10 microns of LLDPE layer, 10 microns of LDPE/LLDPE blend layer, and 10 microns of MPE/LDPE/LLDPE blend layer.

The inner band is the same as Example 1.

Example 7

Pull tab:

Aluminum foil: Tianjin Dongyue, 40 microns.

MPE/LDPE/LLDPE mixture layer: MPE/LDPE/LLDPE=4:1:1.

LLDPE: melt index 2.0, density 0.918 g/cm3, MPE: melt index 1.0, density 0.918 g/cm3, LDPE: melt index 2.0, density 0.924 g/cm3, all of which are mass ratios.

The resins described above were heated and melted, and the layers of the molded multilayer film were 40 microns of aluminum foil and 25 microns of MPE/LDPE/LLDPE blend layer. The inner band is the same as Example 1.

Example 8

Pull tab:

Aluminum foil: Tianjin Dongyue, 40 microns.

LLDPE layer: melt index 2.0, density 0.918 g/cm3

LDPE/LLDPE mixture layer: LDPE/LLDPE=3:1

MPE/LDPE/LLDPE mixture layer: MPE/LDPE/LLDPE=1:1:1.

LLDPE: melt index 2.0, density 0.918 g/cm3, MPE: melt index 1.0, density 0.918 g/cm3, LDPE: melt index 2.0, density 0.924 g/cm3, all of which are mass ratios.

The resins described above were heated and melted, and the layers of the molded multilayer film were 40 microns of aluminum foil and 25 microns of MPE/LDPE/LLDPE blend layer. The inner band is the same as Example 1.

Comparative example 1

Pull tab:

Aluminum foil: Tianjin Dongyue, 40 microns.

LLDPE layer: melt index 2.0, density 0.918 g/cm3

The resins described above were heated and melted, and the layers of the molded multilayer film were 40 microns for the aluminum foil and 25 microns for the LLDPE layer. The inner band is the same as Example 1

Comparative example 2

Pull tab:

Aluminum foil: Tianjin Dongyue, 40 microns.

LDPE layer: melt index 2.0, density 0.924 g/cm3.

The resins as described above were heated and melted, and the layers of the molded multilayer film were 40 microns for the aluminum foil and 25 microns for the LDPE layer. The inner band is the same as Example 1.

Comparative example 3

Pull tab:

Aluminum foil: Tianjin Dongyue, 40 microns.

MPE layer: melt index 1.0, density 0.918 g/cm3.

The resins as described above were heated and melted, and the layers of the molded multilayer film were 40 microns for the aluminum foil and 25 microns for the LDPE layer. The inner band is the same as Example 1.

test methods

Various types of pull tabs and inner tapes can be obtained from the multilayer films obtained in the above examples. Using these various types of inner tapes and tabs, the lower surface of the opening portion sealed with the tab of the paper container shown in FIG. 2 is sealed along the outer periphery, thereby sealing the opening portion from the lower side. When the pull tab in the above example is used to unseal the opening, it is visually observed how the pull tab is broken at a portion near the edge portion of the opening. When the pull-tab is peeled off, the inner tape is cut off quickly, and no part of the inner tape or the pull-tab leaves fibers or small pieces, the test is passed. Conversely, if fibers and small pieces remain on a part of the tab after the inner tape is broken, the test fails.

1000 samples were taken for each type of pull sheet, and the number of qualified samples was determined. The results are shown in Table 1.

Table 1

sample example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 to 1 pair 2 pair 3 qualified% 81 83 79 95 96 98 95 85 56 59 64

The above-mentioned extremely strict test results show that the solution of using MPE/LDPE/LLDPE can greatly reduce the opening effect of the pull tab, while using any one polymer alone cannot achieve a good opening effect. In the above solution, the aforementioned adhesive is added, and the adhesive is prepared by the aforementioned preparation method. Example 1-3 can improve the pass rate by at least 19%.

The foregoing examples are illustrative only, used to explain some of the features of the present disclosure. The appended claims are intended to claim the broadest scope conceivable and the embodiments presented herein are merely illustrations of selected implementations according to all possible combinations of embodiments. Accordingly, it is the applicant's intention that the appended claims not be limited by the selection of examples which characterize the invention. Moreover, advances in science and technology will create possible equivalents or sub-replacements not presently considered due to inaccuracies of language, and these changes should also be construed to be covered by the appended claims where possible .

Claims (2)

1. Pull tab, including layers in the following order: aluminum foil layer, LLDPE layer, LDPE/LLDPE mixture layer, MPE/LDPE/LLDPE mixture layer; The LDPE/LLDPE mixture layer is arranged between the aluminum foil layer and the MPE/LDPE/LLDPE mixture layer; The LLDPE layer is arranged between the aluminum foil layer and the LDPE/LLDPE mixture layer; The mass ratio of the LDPE to the LLDPE in the LDPE/LLDPE mixture layer is 1:3; The mass ratio of the MPE to the LDPE and the LLDPE in the MPE/LDPE/LLDPE mixture layer is 1:1:1. 2. A packaging container, the packaging container includes a packaging container main body, the packaging container main body includes an opening set on the top of the container for pouring out food, the opening is covered by a pull tab, and is drawn along the opening from above the pull tab The outer periphery of the opening is sealed, the opening is covered by the inner tape from below, and the lower surface of the outer periphery of the opening and the inner surface of the handle are welded together, and the handle is the handle described in claim 1 .