Sheet-like composite, especially packaging laminate for dimensionally stable foodstuff containers, having a polymeric intermediate layer characterized by differential scanning calorimetry

Abstract

The invention relates to a sheet-like composite including as layers of a layer sequence, in a direction from an external side of the sheet-like composite to an internal side of the sheet-like composite, a) a carrier layer, b) a polymeric intermediate layer, and c) a barrier layer, where a graph of differential scanning calorimetry of the polymeric intermediate layer includes a peak A at a temperature T.sub.A and a peak B at a temperature T.sub.B, where the temperature TB is more than the temperature T.sub.A, where a width of the peak B is less by at least 3 C. than a width of the peak A. The invention further relates to a container precursor and to a closed container including the sheet-like composite, and also to a process by which the sheet-like composite is obtainable, and to a use of the sheet-like composite.

Claims

1. A laminate including as layers of a layer sequence, in a direction from an external side of the laminate to an internal side of the laminate, a) a polymeric external layer, wherein the polymeric external layer comprises a polyolefin, b) a carrier layer, wherein the carrier layer includes a material selected from the group consisting of cardboard, paperboard, paper, and a combination of at least two thereof; c) a polymeric intermediate layer, wherein the polymeric intermediate layer comprises a polyolefin, and d) a barrier layer, where a graph of differential scanning calorimetry of the polymeric intermediate layer includes a peak A at a temperature T.sub.A and a peak B at a temperature T.sub.B, where the temperature T.sub.B is more than the temperature T.sub.A, where a width of the peak B is less by at least 3 C. than a width of the peak A, where the polymeric intermediate layer comprises a first intermediate layer and a second intermediate layer, wherein the first intermediate layer comprises from 20-70 wt. % HDPE, based on the total weight of the first intermediate layer, and 30-80% wt. % of LDPE, based on the total weight of the first intermediate layer; and where the polyolefin in the polymeric intermediate layer does not include LLDPE; wherein the polyolefin in the polymeric external layer does not consist of a polyethylene prepared using a metallocene catalyst (mPE).

2. The laminate according to claim 1, where the temperature T.sub.A is at least 80 C.

3. The laminate according to claim 1, where the peak A is characterized by an enthalpy of fusion H.sub.A, where the peak B is characterized by an enthalpy of fusion H.sub.B, where a ratio of the enthalpy of fusion H.sub.A to the enthalpy of fusion H.sub.B is in a range from 1:4 to 1:0.3.

4. The laminate according to claim 1, where an absolute value of a difference between the temperature T.sub.B and the temperature T.sub.A is at least 10 C.

5. The laminate according to claim 1, where an absolute value of a difference between the temperature T.sub.B and the temperature T.sub.A is not more than 40 C.

6. The laminate according to claim 1, where an absolute value of a difference between an extrapolated start temperature of the peak B and an extrapolated end temperature of the peak A is in a range from 5 to 20 C.

7. A container precursor including the laminate according to claim 1.

8. The container precursor according to claim 7, where the laminate has at least 3 folds.

9. The container precursor according to claim 7, where the laminate includes a first longitudinal edge and a further longitudinal edge, the first longitudinal edge being joined to the further longitudinal edge forming a longitudinal seam of the container precursor.

10. A closed container comprising the laminate according to claim 1.

11. The closed container according to claim 10, where the laminate includes a first longitudinal edge and a further longitudinal edge, the first longitudinal edge being joined to the further longitudinal edge forming a longitudinal seam of the closed container.

12. The closed container according to claim 11, where the closed container contains a foodstuff.

13. The laminate according to claim 1, wherein the polymeric intermediate layer further comprises an adhesion promoter.

14. The laminate according to claim 13, wherein the adhesion promoter comprises a polyethylene-maleic anhydride graft polymer, an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, or a combination thereof.

15. The laminate according to claim 1, wherein the second intermediate layer comprises an adhesion promoter.

16. A laminate including as layers of a layer sequence, in a direction from an external side of the laminate to an internal side of the laminate, a) a polymeric external layer, wherein the polymeric external layer comprises a polyolefin b) a carrier layer, c) a polymeric intermediate layer, wherein the polymeric intermediate layer comprises a polyolefin, and d) a barrier layer, where a graph of differential scanning calorimetry of the polymeric intermediate layer includes a peak A at a temperature T.sub.A and a peak B at a temperature T.sub.B, where the temperature T.sub.B is more than the temperature T.sub.A, where a width of the peak B is less by at least 3 C. than a width of the peak A, wherein the polymeric intermediate layer comprises from 20-70 wt. % HDPE, based on the total weight of the intermediate layer, and 30-80% wt. % of LDPE, based on the total weight of the intermediate layer, where the polymeric intermediate layer does not include LLDPE; wherein the polyolefin in the polymeric external layer does not consist of a polyethylene prepared using a metallocene catalyst (mPE).

17. The laminate according to claim 1 or 16, where the polyolefin in the polymeric external layer does not include mPE.

18. The laminate according to claim 1 or 16, where the polymeric external layer consists of LDPE.

Description

(1) Unless indicated otherwise in the description or in the respective figure, the following is shown in each case, diagrammatically and not true to scale:

(2) FIG. 1 shows a sheet-like composite of the invention in a cross section;

(3) FIG. 2 shows a diagrammatic graph of a differential scanning calorimetry measurement of the polymeric intermediate layer of FIG. 1;

(4) FIG. 3 shows a container precursor of the invention;

(5) FIG. 4 shows a closed container of the invention;

(6) FIG. 5 shows a flow diagram of a process of the invention;

(7) FIG. 6 shows a flow diagram of another process of the invention;

(8) FIG. 7 shows a flow diagram of another process of the invention; and

(9) FIG. 8 shows a graph of a differential scanning calorimetry measurement of a polymeric intermediate layer of a sheet-like composite of the invention.

(10) FIG. 1 shows a sheet-like composite 100 of the invention in a cross section. The sheet-like composite 100 includes as layers of a layer sequence, in a direction from an external side 101 of the sheet-like composite 100 to an internal side 102 of the sheet-like composite 100, an colour layer 108, a polymeric external layer 107 of LDPE, a carrier layer 106 of cardboard, a polymeric intermediate layer 105 as laminating layer, a barrier layer 104 of aluminium, and a polymeric internal layer 103. A graph 201 of a differential scanning calorimetry of the polymeric intermediate layer 105 is shown in FIG. 2. The polymeric intermediate layer 105 includes an HDPE in a fraction of 45 wt %, based on the total weight of the polymeric intermediate layer 105. Furthermore, the polymeric intermediate layer 105 consists of the following sublayers of a sublayer sequence, in a direction from the external side 101 to the internal side 102: a first intermediate layer 109 of 50 wt % HDPE and 50 wt % 23L430 from Ineos Kln GmbH, in each case based on the total weight of the first intermediate layer 109, and a further intermediate layer 110 of 100 wt % Novex M21N430 from Ineos Kln GmbH, based on the total weight of the further intermediate layer 110. The polymeric internal layer 103 includes an HDPE in a fraction of 17 wt %, based on the total weight of the polymeric internal layer 103. Furthermore, the polymeric internal layer 103 consists of the following sublayers (not shown) of a sublayer sequence, in a direction from a side of the polymeric internal layer 103 that faces the barrier layer 104, to the internal side 102: a first internal layer of 75 wt % HDPE and 25 wt % LDPE, based in each case on the total weight of the first internal layer; a second internal layer of 100 wt % LDPE, based on the total weight of the second internal layer; and a third internal layer of a polymer blend, the polymer blend consisting of 30 wt % of an mPE and 70 wt % of an LDPE, based in each case on the total weight of the third internal layer. A graph of a differential scanning calorimetry measurement of the polymeric internal layer 103 has inventive peaks C and D, in particular with respect to the widths and enthalpies of fusion H.sub.C and H.sub.D thereof.

(11) FIG. 2 shows a schematic graph 201 of a differential scanning calorimetry measurement of the polymeric intermediate layer 105 from FIG. 1. Plotted here are the heat flow dQ/dt against the temperature T in C. The graph includes a peak A at a temperature T.sub.A and a peak B at a temperature T.sub.B. The temperature T.sub.B is more than the temperature T.sub.A=105 C., with the difference between the two being 25 C. A width 210 of the peak B is smaller by 12 C. than a width 202 of the peak A. In this case the width 210 of the peak B is equal to a difference between an extrapolated end temperature 208 of the peak B and of an extrapolated start temperature 207 of the peak B. A width 202 of the peak A is equal to a difference between an extrapolated end temperature 206 of the peak A and an extrapolated start temperature 205 of the peak A. A difference 203 between the extrapolated start temperature 207 of the peak B and the extrapolated end temperature 206 of the peak A is 15 C. The extrapolated start and end temperatures 205-208 were determined by means of auxiliary lines 209. An enthalpy of fusion H.sub.A of peak A is 47 J/g. An enthalpy of fusion H.sub.B of peak is 23 J/g. Definitions of the terms used are found, as also indicated above, in DIN EN ISO 11357-1:2010-03.

(12) FIG. 3 shows a container precursor 300 of the invention. The container precursor 300 includes the sheet-like composite 100 of FIG. 1 with 4 folds 301. The sheet-like composite 100 is a blank for producing an individual closed container 400. The container precursor 200 is jacket-like and includes a longitudinal seam 302, in which a first longitudinal edge and a further longitudinal edge of the sheet-like composite 100 are sealed to one another. Further, the container precursor 300 includes a hole 305 in the carrier layer 106. The hole 305 is covered by the polymeric intermediate layer 105, the barrier layer 104 and the polymeric internal layer 103. By folding along grooves 306 and connecting of folding regions in a top region 303 and a base region 304 of the container precursor 300, a closed container 400 is obtainable. A closed container 400 of this kind is shown in FIG. 4.

(13) FIG. 4 shows a closed container 400 of the invention. The closed container 400 is produced from the container precursor 300 according to FIG. 3. The closed container 400 contains a foodstuff 401 and has 12 edges 403. Further, the closed container 400 is joined to an opening aid 402, which covers the hole 305 on the external side 101 of the sheet-like composite 100. Here, the opening aid 402 includes a lid and a cutting tool connected to the lid in its interior.

(14) FIG. 5 shows a flow diagram of a process 500 of the invention for producing a sheet-like composite 100. The process 500 includes process steps a) 501 and b) 502. In process step a) 501, a carrier layer 106 of cardboard in roll form, a barrier layer 104 of aluminium in roll form, a first polymer composition and a further polymer composition are provided. In process step b) 502, the barrier layer 104 and the carrier layer 106 are joined to one another. This is done by laminating the barrier layer 104 to the carrier layer 106 using the first polymer composition and the further polymer composition as laminating agents. The laminating is performed as thermolaminating. In this operation, the carrier layer 106 is contacted with the first polymer composition, and the barrier layer 104 with the further polymer composition. Furthermore, the first polymer composition and the further polymer composition are contacted with one another. As a result of this procedure, a sheet-like composite 100 including as layers of a layer sequence, in a direction from an external side 101 of the sheet-like composite 100 to an internal side 102 of the sheet-like composite 100: the carrier layer 106, a first intermediate layer 109, formed from the cooled first polymer composition, a further intermediate layer 110, formed from the cooled further polymer composition, and the barrier layer 104. The first intermediate layer 109 and the further intermediate layer 110 together form a polymeric intermediate layer 105 of the invention. The first polymer composition consists to an extent of 70 wt % of an HDPE and 30 wt % of Novex 23L430 from Ineos Kln GmbH, based in each case on the total weight of the first polymer composition. The further polymer composition consists to an extent of 100 wt % of Novex M21N430 from Ineos Kln GmbH, based on the total weight of the further polymer composition.

(15) FIG. 6 shows a flow diagram of another process 600 of the invention for producing a container precursor 300. In a process step A. 601, the sheet-like composite 100 of FIG. 1 is provided. It includes a first longitudinal edge and a further longitudinal edge. In a process step B. 602, the sheet-like composite 100 is folded. In a process step C. 603, the first longitudinal edge and the further longitudinal edge are pressed onto one another and joined to one another by ultrasonic sealing. This produces a longitudinal seam 302. The container precursor 300 of FIG. 3 is produced according to the above description.

(16) FIG. 7 shows a flow diagram of another process 700 of the invention for producing a closed container 400. In a process step a. 701, the container precursor 300 of FIG. 3 is provided. In a process step b. 702, a base region 304 of the container precursor 300 is formed by folding of the sheet-like composite 100. In a process step c. 703, the base region 304 is closed by sealing with hot air at a temperature of 300 C. In a process step d. 704, the container precursor 300 is filled with a foodstuff 401, and in a process step e. 705 the container precursor 300 is closed in a top region 303 by sealing, obtaining the closed container 400. In a process step f. 706, the closed container 400 is joined to an opening aid 402.

(17) FIG. 8 shows a graph 201 of a differential scanning calorimetry measurement of a polymeric intermediate layer 105 of a sheet-like composite 100 of the invention. The sheet-like composite 100 includes as layers of a layer sequence, in a direction from an external side 101 of the sheet-like composite 100 to an internal side 102 of the sheet-like composite 100, an colour layer 108, a polymeric external layer 107 of LDPE, a carrier layer 106 of cardboard, the polymeric intermediate layer 105 as laminating layer, a barrier layer 104 of aluminium, and a polymeric internal layer 103. The polymeric intermediate layer 105 includes an HDPE in a fraction of 50 wt %, based on the total weight of the polymeric intermediate layer 105, and Novex M21N430 from Ineos Kln GmbH in a fraction of 50 wt %, based on the total weight of the polymeric intermediate layer 105. The differential scanning calorimetry measurement was carried out as described in the measurement method above, more particularly with the stated heating rates, the hold time and the cooling rate. The graph 201 depicted comes from the measurement of the second heating rate. Plotted in FIG. 8 are the heat flow dQ/dt in mW against the temperature T in C. Also to be seen in FIG. 8 are a peak A at a temperature T.sub.A=105.37 C. and a peak B at a temperature T.sub.B=127.53 C., in each case above a virtual interpolated baseline 801. Peak A has an enthalpy of fusion H.sub.A and peak B an enthalpy of fusion H.sub.B. Peak A is characterized by an extrapolated start temperature 205 of 91.39 C. and an extrapolated end temperature 206 of 118.90 C. Peak B is characterized by an extrapolated start temperature 207 of 123.82 C. and an extrapolated end temperature 208 of 129.00 C. For determining the extrapolated start temperatures 205 and 207 and the extrapolated end temperatures 207 and 208, auxiliary lines 209 are used as tangents to points of inflection of the respective peak, as described on page 11 of DIN EN ISO 11357-1:2010-03.

LIST OF REFERENCE NUMERALS

(18) 100 sheet-like composite of the invention 101 external side 102 internal side 103 polymeric internal layer 104 barrier layer 105 polymeric intermediate layer 106 carrier layer 107 polymeric external layer 108 colour layer 109 first intermediate layer 110 further intermediate layer 201 graph 202 width of peak A 203 difference between an extrapolated start temperature of peak B and an extrapolated end temperature of peak A 204 difference between the temperature T.sub.B and the temperature T.sub.A 205 extrapolated start temperature of peak A 206 extrapolated end temperature of peak A 207 extrapolated start temperature of peak B 208 extrapolated end temperature of peak B 209 auxiliary line 210 width of peak B 300 container precursor of the invention 301 fold 302 longitudinal seam 303 top region 304 base region 305 hole 306 groove 400 closed container of the invention 401 foodstuff 402 opening aid 403 edge 500 process of the invention for producing a sheet-like composite 501 process step a) 502 process step b) 600 process of the invention for producing a container precursor 601 process step A. 602 process step B. 603 process step C. 700 process of the invention for producing a closed container 701 process step a. 702 process step b. 703 process step c. 704 process step d. 705 process step e. 706 process step f. 801 virtual interpolated baseline