Aluminium barrier laminate and barrier liner at shoulder for container

Abstract

A laminate sheet, particularly an aluminium-based laminate comprises polyethylene having a density of 0.90-0.96 g/cc, a polyethylene-based film having a melting temperature of less than 240° C.; low density polyethylene in order to provide high adhesion; an aluminium barrier film, and a polyethylene-based film having a sealing property. Furthermore, the laminate sheet may further comprise a blown film or a dry laminate for making a tube and a tube shoulder in order to prevent flavor loss of the products packaged therein and without stress crack.

Claims

1. A laminate comprising: a first layer having a polyethylene-based film with a density of 0.90-0.96 g/cc; a second layer having a linear low density polyethylene-based film with a melting temperature of less than 240° C.; a third layer having low density polyethylene in order to provide high adhesion; a fourth layer adjacent to the third layer having an aluminum barrier film with a thickness of 7-20 microns; a fifth layer adjacent to the fourth layer having low density polyethylene that provides in order to provide high interlayer adhesion; a sixth layer having a linear low density polyethylene-based film with a melting temperature of less than 240° C.; and a seventh layer having a polyethylene-based film with a sealing property, wherein the seventh layer is a 5-layer blown film comprising a resin with barrier properties, wherein the resin with barrier properties comprises EVOH, wherein the seventh layer is the innermost layer in the laminate.

2. The laminate of claim 1, wherein the first layer comprises a polyolefin film layer which is a monolayer film or a multilayer film.

3. The laminate of claim 1, wherein the first layer comprises a blend of one or more types of material selected from the group consisting of low density polyethylene, or linear low density polyethylene, and high density polyethylene.

4. The laminate of claim 1, wherein an outside of the first layer is by a surface printing.

5. The laminate of claim 1, wherein the low density polyethylene of the third layer and the fifth layer is a high interlayer adhesive copolymer selected from the group consisting of ethylene acrylic acid (EAA) copolymers, ethylene vinyl acetate, ethylene methacrylic acid, maleic anhydride copolymers, and mixture thereof.

6. The laminate of claim 1, wherein the fourth layer has a thickness in the range of 7-12 microns.

7. The laminate of claim 1, wherein the laminate has a structure comprising: the first layer having a thickness in the range of 50-100 microns; the second layer having a thickness in the range of 18-25 microns; the third layer having a thickness in the range of 18-25 microns; the fourth layer having an aluminum barrier film with a thickness of 8 microns; the fifth layer having a thickness in the range of 18-25 microns; the sixth layer having a thickness in the range of 18-25 microns; and the seventh layer having a thickness in the range of 40-100 microns.

8. The laminate of claim 1, wherein the laminate is a membrane rondelle film wherein: the first layer having a thickness in the range of 25-60 microns; the second layer having a thickness in the range of 5-18 microns; the third layer having a thickness in the range of 5-18 microns; the aluminum barrier film of the fourth layer has a thickness of 8 microns; the fifth layer having a thickness in the range of 5-18 microns; the sixth layer having a thickness in the range of 5-18 microns; and the seventh layer having a thickness in the range of 25-60 microns.

9. The laminate of claim 1, wherein the first layer consists of polyolefin.

10. The laminate of claim 1, wherein the laminate has an oxygen transmission rate as measured according to ASTM D3985 that is 0.031 or less and a water vapor transmission rate as measured according to ASTM F1249 that is 0.038 or less.

11. A laminate tube comprising the laminate of claim 1 and a shoulder region in which an internal barrier liner is formed as a hollow cylindrical extension portion with a closure diaphragm, wherein the shoulder region is manufactured by a procedure comprising steps of: punching the laminate into a shape of a tube shoulder having a diameter of 5-15% larger than that of the tube shoulder; mounting the punched laminate to a mandrel tip where the tube body is already preloaded in order to obtain the mandrel mounted with the tube body; moving the mandrel mounted with the tube body and the laminate to a next station where a doughnut-shaped HDPE is dosed inside a shoulder mold; closing and compressing the shoulder mold and the mandrel mounted with the tube body and the laminate in order to form a desired shape of the shoulder; fixing the laminate permanently to an inner dome surface of the compression-molded tube shoulder; and fusing the laminate with the melted doughnut-shaped HDPE, thereafter forming permanent bond together with the composite laminate in order to obtain the tube shoulder.

12. The laminate of claim 11, wherein the laminate has an oxygen transmission rate as measured according to ASTM D3985 that is 0.031 or less and a water vapor transmission rate as measured according to ASTM F1249 that is 0.038 or less.

13. A laminate tube having the laminate as claimed in claim 1, wherein the tube is manufactured by a procedure comprising steps of: punching the laminate into a shape of the tube shoulder having a diameter of 5-15% larger than that of the tube shoulder; mounting the punched laminate to a mandrel tip where the tube body is already preloaded in order to obtain the mandrel mounted with the tube body; moving the mandrel mounted with the tube body and the laminate to a next station where a doughnut-shaped HDPE is dosed inside a shoulder mold; closing and compressing the shoulder mold and the mandrel mounted with the tube body and the laminate in order to form a desired shape of the shoulder; fixing the laminate permanently to an inner dome surface of the compression-molded tube shoulder; and fusing the laminate with the melted doughnut-shaped HDPE, thereafter forming permanent bond together with the composite laminate in order to obtain the tube shoulder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a cross-sectional view of a layer structure of a laminate sheet 1 comprising polyethylene film layers 4, co-extruded polyethylene layers 5, co-extruded EAA layers 6, and an aluminium foil layer 7.

(2) FIG. 2 shows a cross-sectional view of a layer structure of a laminate sheet 2 comprising a polyethylene film layer 4, co-extruded polyethylene layers 5, EAA layers 6, an aluminium foil layer 7, and a 5-multilayer film 8 composed of polyethylene/tie/EVOH/tie/polyethylene having a thickness of 40-100 microns.

(3) FIG. 3 shows a cross-sectional view of a layer structure of a laminate sheet 3 comprising polyethylene film layers 4, a co-extruded polyethylene layer 5, an EAA layer 6, an aluminium foil layer 7, and a laminate adhesive 9.

(4) FIG. 4 shows a schematic view of a shoulder region of a tube in which an internal barrier liner is formed as a hollow cylindrical extension portion with a closure diaphragm, wherein FIG. 4(a) shows a top view, FIG. 4(b) shows a side view, FIG. 4(c) shows a side view without the internal barrier liner, and FIG. 4(d) shows a side view with the internal barrier liner.

DETAILED DESCRIPTION

(5) Advantages of the subject matter will become apparent with regard to the following description, appended claims, and accompanying drawings.

(6) In this invention, an aluminium barrier laminate structure comprises at least 7 or more layers in total as follows: an outer polyethylene layer; a co-extruded polyethylene layer, a co-extruded EAA (ethylene acrylic acid) layer; a core aluminium layer; a co-extruded EAA layer; a co-extruded polyethylene layer; and an inner polyethylene layer.

(7) In one embodiment, the laminate according to this invention comprises:

(8) a first layer which is a polyethylene-based film having a density of 0.90-0.96 g/cc, wherein: the first layer comprises a polyolefin film layer which may be a monolayer film or a multilayer film, and the outside of the first layer may optionally be printed by a surface printing; furthermore; the first layer may comprise a blend of one or more types of material selected from low density polyethylene, or linear low density polyethylene, or high density polyethylene; and the first layer preferably has a thickness in the range of 50-100 microns;

(9) a second layer which is a polyethylene-based film having a melting temperature of less than 240° C., wherein the second layer is a polyethylene film having a density of 0.85-0.94 g/cc, and the second layer preferably has a thickness in the range of 18-25 microns;

(10) a third layer which is low density polyethylene to provide high adhesion, wherein: a high interlayer adhesive is preferably selected from acid copolymers which is selected from ethylene acrylic acid (EAA) copolymers, ethylene vinyl acetate, ethylene methacrylic acid, maleic anhydride copolymers, or mixture thereof; and the third layer preferably has a thickness in the range of 18-25 microns;

(11) a fourth layer having an aluminium barrier film, wherein the fourth layer has a thickness of 7-20 microns, preferably in the range of 7-12 microns, and more preferably in the range of 8-9 microns;

(12) a fifth layer having low density polyethylene to provide high interlayer adhesion, wherein: a high interlayer adhesive is preferably selected from acid copolymers which is selected from ethylene acrylic acid (EAA) copolymers, ethylene vinyl acetate, ethylene methacrylic acid, maleic anhydride copolymers, or mixture thereof; and the fifth layer preferably has a thickness in the range of 18-25 microns;

(13) a sixth layer having a polyethylene-based film with a melting temperature of less than 240° C., wherein the sixth layer is a polyethylene film having a density of 0.85-0.94 g/cc, and the sixth layer preferably has a thickness in the range of 18-25 microns; and

(14) a seventh layer having a polyethylene-based film with a sealing property which is a monolayer film, a multilayer film, preferably a 3-layer film, 5-layer blown film, or a blend of 90% to 99% of polyolefin and 1% to 10% of polyolefin elastomer; and the seventh layer preferably has a thickness in the range of 40-100 microns.

(15) In one embodiment, a process for preparation of the laminate according to this invention comprises: extrusion of high density polyethylene (HDPE) and linear low density polyethylene (LLDPE) by a blown film extrusion process in order to improve physical properties of the film. A 3 to 5-layer blown film can be used by selecting various resin materials having capability of mixing and good properties thereof. Resin material selection can be varied such as HDPE, LDPE, LLDPE, nylon, EVOH, tie, and other materials. In case of the 5-layer blown film, the EVOH layer is selected in order to provide aroma barrier property to the laminate sheet. A co-extrusion procedure can be generally used for forming the co-extruded film. The tie layer is necessary for adhesion of the polyethylene layer and the EVOH layer. The outer layer uses a 3-layer blown film due to features of capability of printing on the outside and the strong middle portion. The inner layer used a 5-layer blown film (polyolefin/tie/EVOH, tie/polyolefin) is used for providing aroma barrier in order to produce the outer layer or the inner layer.

(16) In one embodiment, the laminate according to this invention as mentioned above which a membrane structure is a membrane rondelle film comprises:

(17) the first layer having a thickness in the range of 25-60 microns;

(18) the second layer having a thickness in the range of 5-18 microns;

(19) the third layer having a thickness in the range of 5-18 microns;

(20) the fourth layer having the aluminium barrier film with a thickness of 8 microns;

(21) the fifth layer having a thickness in the range of 5-18 microns;

(22) the sixth layer having a thickness in the range of 5-18 microns; and

(23) the seventh layer having a thickness in the range of 25-60 microns.

(24) More specifically, in the first embodiment, a laminate tube according to this invention preferably is formed from a laminate 1 having at least seven layers, wherein the laminate comprises: a central layer 7 which has a barrier property or blocking effect comprising an aluminium foil layer 7; and an EAA layer 6 located on both sides of the central layer 7, a co-extruded polyethylene layer 5, and a polyethylene film layer 4, which the polyethylene (PE) may be LDPE (low density polyethylene), HDPE (high density polyethylene), LLDPE (linear low density polyethylene) or mixtures thereof, as shown in FIG. 1.

(25) More specifically, in one embodiment, a laminate tube according to this invention preferably is formed from a laminate 2 having at least seven layers, wherein the laminate comprises: a central layer 7 which has a barrier property or blocking effect comprising an aluminium foil layer 7; an EAA layers 6 located on both sides of the central layer 7, a co-extruded polyethylene layer 5, and a polyethylene film layer 4, which the polyethylene (PE) may be LDPE (low density polyethylene), HDPE (high density polyethylene), LLDPE (linear low density polyethylene) or mixtures thereof; and a laminate film layer 8 comprising polyethylene/tie/EVOH/tie/polyethylene having a thickness in the range of 40-100 microns, as shown in FIG. 2, in which the polyethylene in the laminate film layer 8 may be LDPE (low density polyethylene), HDPE (high density polyethylene), LLDPE (linear low density polyethylene) or mixtures thereof.

(26) In one embodiment, the outer polyethylene layer and the inner polyethylene layer may independently be a monolayer or multilayer film, preferably a three-layer film.

(27) In one embodiment, a laminate according to this invention comprises:

(28) a first layer having a polyethylene-based film with a density of 0.90-0.95 g/cc, wherein the first layer preferably has a thickness in the range of 50-100 microns;

(29) a second layer with a dry lamination, wherein the second layer preferably has a thickness in the range of 0.5-5 microns;

(30) a third layer with a barrier property, wherein the third layer preferably has an aluminium barrier film having a thickness in the range of 7-20 microns, preferably in the range of 7-12 microns, and more preferably in the range of 8-9 microns;

(31) a fourth layer having low density polyethylene to provide high interlayer adhesion, wherein the fourth layer preferably has a thickness in the range of 18-25 microns;

(32) a fifth layer having a polyethylene-based film with a melting temperature of less than 240° C., wherein the sixth layer preferably has a thickness in the range of 18-25 microns; and

(33) a sixth layer having a polyethylene-based film with a sealing property, wherein the sixth layer preferably has a thickness in the range of 40-100 microns.

(34) In one embodiment, a laminate tube according to this invention preferably is formed from a laminate 3 having at least seven layers, wherein the laminate comprises: a central layer 7 which as a barrier property or blocking effect comprising an aluminium foil layer 7; a EAA layers 6; a co-extruded polyethylene or polyolefin layer 5; polyethylene layers 4, which the polyethylene (PE) may be LDPE (low density polyethylene), HDPE (high density polyethylene), LLDPE (linear low density polyethylene) or mixtures thereof; and a laminate adhesive 9 used herein for adhering the aluminium foil and polyolefin, as shown in FIG. 3.

(35) Dry lamination or extrusion coating has cost-benefit as comparing to extrusion lamination due to a lower coating weight of raw material. Two component adhesive such as polyurethane are usually used in this procedure. The inner film is laminated by means of extrusion on one side of the aluminium foil. The outer film is dry-laminated by using an adhering agent on the other side of said aluminium foil. The extrusion lamination on the inner side of the packaging is selected, due to a high bonding strength obtained from this technique. The bond strength of more than 500 g/15 mm can prevent delamination for the laminated side contacted to liquid bulks.

(36) A tube portion which is illustrated a laminate cross-section. Each of the tube portions 1 to 3 together with a head is generally described in FIG. 4, which shows a schematic view of a shoulder region of the tube, in which an internal barrier liner is formed as a hollow cylindrical extension portion with a closure diaphragm.

(37) The laminate tube body comprises: an outer layer of 50% to 30% of high density polyethylene (HDPE) and 50% to 70% of linear low density polyethylene (LLDPE); an aluminium core layer between ethylene acrylic acid (EAA) layers; and an inner layer of 50% to 30% of high density polyethylene (HDPE) and 50% to 70% of linear low density polyethylene (LLDPE). The linear low density polyethylene (LLDPE) has a density of 0.912 g/cc to 0.94 g/cc, and the high density polyethylene (HDPE) has a density of about 0.93 g/cc to 0.97 g/cc.

(38) The low density polyethylene (LDPE) used in the present invention preferably has a density of around 0.918 g/cc to 0.935 g/cc, preferably 0.918 glee.

(39) Furthermore, in another embodiment, a laminate comprises: an outer layer of 30% to 50% of high density polyethylene (HDPE) and/or 50% to 70% linear low density polyethylene (LLDPE) having a thickness of 70-100 microns; an ethylene acrylic acid (EAA) layer having a thickness of 15-40 microns; an aluminium core layer having a thickness of 8-12 microns; and an inner layer of 50% to 30% of high density polyethylene (HDPE) and/or 50% to 70% of linear low density polyethylene (LLDPE) having a thickness of 40-70 microns.

(40) In a case of using the aluminium layer having a thickness of less than 9 microns, high voltage of ozone treatment and high pressure at the nip rolls are necessary in order to provide optimum bonding strength (g/15 mm, 180 degrees). Sample 4 is used for packaging liquid or paste having aroma and flavor in order to prevent oxygen and aroma loss. Extrusion coating or dry lamination is applied on one side of the laminate sheet for decreasing cost and a total thickness.

(41) In one embodiment, a laminate at a tube shoulder according to this invention is manufactured by a procedure comprising steps of:

(42) punching the laminate into a shape of the tube shoulder having a diameter of 5-15% larger than that of the tube shoulder;

(43) mounting the punched laminate to a mandrel tip where the tube body is already preloaded in order to obtain the mandrel mounted with the tube body;

(44) moving the mandrel mounted with the tube body and the laminate to a next station where a doughnut-shaped HDPE is dosed inside a shoulder mold;

(45) closing and compressing the shoulder mold and the mandrel mounted with the tube body and the laminate in order to form a desired shape of the shoulder;

(46) fixing the laminate permanently to an inner dome surface of the compression-molded tube shoulder; and

(47) fusing the laminate with the melted doughnut-shaped HDPE, thereafter forming permanent bond together with the composite laminate in order to obtain the tube shoulder.

(48) In one embodiment of this invention, a laminate tube having the laminate as mentioned above is also provided, wherein the tube shoulder is manufactured from a melt-blended resin comprising 50-90% of HDPE, 5-15% of LLDPE, and 5-35% of a cyclic olefin copolymer.

(49) Samples

(50) TABLE-US-00001 TABLE 1 Laminate Structures Detail/Thickness (microns) 1.sup.st 2.sup.nd 3.sup.rd 4.sup.th 5.sup.th 6.sup.th 7.sup.th Samples Total Layer Layer Layer Layer Layer Layer Layer Sample 200 Polyolefin/ LLDPE/ EAA/ Al EAA/ LLDPE/ Polyolefin/ 1 70 14 14 Foil/12 20 20 50 Sample 250 Polyolefin/ LLDPE/ EAA/ Al EAA/ LLDPE/ Polyolefin/ 2 100 18 18 Foil/12 34 18 50 Sample 199 Polyolefin/ LLDPE/ EAA/ Al EAA/ LLDPE/ Polyolefin/ 3 70 15 15 Foil/9 20 20 50 Sample 250 Polyolefin/ LLDPE/ EAA/ Al EAA/ LLDPE/ 5-Layer 4 100 18 18 Foil/12 34 18 Blown Film/50 Sample 200 Polyolefin/ Dry Al EAA/ LLDPE/ Polyolefin/ — 5 85 Laminate/3 Foil/12 25 25 50

(51) TABLE-US-00002 TABLE 2 OTR and WVTR of Laminates OTR* WVTR* at 23° C., 0% at 38° C., RH 90% RH Samples cc/m.sup.2 .Math. day g/m.sup.2 .Math. day Sample 1 0.031 0.043 Sample 2 0.030 0.040 Sample 3 0.031 0.024 Sample 4 0.031 0.030 Sample 5 0.033 0.038 *OTR tests are subjected to ASTM D3985, whereas WVTR tests are subjected to ASTM F1249.

(52) Samples 1-2 are conventional laminate structures, and samples 3-5 are laminate structures of this invention, as shown in Table 1.

(53) OTR (oxygen transmission rate) and WVTR (water vapor transmission rate) are important values in shelf life evaluation of products in a packaging. The controlled OTR is generally desired in order to obtain quality, safety, and shelf life of the packaging. The WVTR is important for humidity-susceptive food and medicine in a packaging.

(54) The oxygen gas transmission rate (OTR) and water vapor transmission rate (WVTR) of all laminate sheets are clearly shown in Table 2. Sample 1 has the same 0 value as sample 3 even though the thickness of the aluminium foil is decreased from 12 microns to 9 microns. Sample 2 has the better OTR value than that of sample 4 by about 3%. In this case, the five-layer blown film with EVOH may prevent aroma loss from the packaging tube. Sample 5 with the dry lamination technique shows the OTR value of 0.033. Samples 3-5 have OTR values almost comparable to those of the samples 1 and 2.

(55) The WVTR test results of samples 3-5 are improved to provide a better barrier packaging. The WVTR of Sample 3 is better than that of sample 1 by 44%. Moreover, the WVTR of Sample 4 is better than that of sample 2 by 25%. In addition, the WVTR of Sample 5 is better than that of sample 1 by 12%. It is seem that the samples 3-5 can be used for packaging solid and liquid products.

(56) The laminate having a thickness of approximate 150-300 microns is usually used for making the tube. The laminate with the lower thickness for making the tube may not pass burst test and drop test.

(57) Stress Crack Test

(58) Stress crack resistance experiments were performed with aggressive hair color cream at the tube shoulder. In general, a laminate tube with an internal barrier liner in the form of the plate-shaped disc could not tolerate that stress crack test. Tube samples 3-5 with the plate-shaped disc were filled with the hair color cream at 50° C. A duplicate set of the samples with a hollow cylindrical extension portion with a closure diaphragm were filled and stored at 50° C. Stress crack failures were appeared in the tubes with the plate-shaped disc after 3 days, while the tube samples with the hollow-cylindrical extension portion with the closure diaphragm show no failure after 1 month.

(59) Therefore, it is clearly seen that this invention provides the laminate tube having improved stress crack resistance and oxygen permeation resistance better than other conventional packaging tubes.

(60) As various specific examples have been described above, these specific examples should not be regarded as limitations to the scope of any embodiments, but they are only illustrations of the preferred embodiments. It is possible that other various variations are also regarded as falling within the spirit according to various embodiments.