Sheet-like composite, especially packaging laminate for dimensionally stable food-stuff containers, having a polymeric internal 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 barrier layer, and c) a polymeric internal layer, where a graph of a differential scanning calorimetry of the polymeric internal 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. 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 carrier layer which includes one selected from the group consisting of cardboard, paperboard, paper and a combination of at least two thereof, b) a barrier layer, and c) a polymeric internal layer, where a graph of a differential scanning calorimetry of the polymeric internal 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 internal layer has a density in the range from 0.890 g/cm.sup.3 to 0.980 g/cm.sup.3 and includes as sublayers of a sublayer sequence, in a direction from a side of the polymeric internal layer that faces the barrier layer, to the inside, a] a first internal layer which consists to an extent of 100 wt %, based on the total weight of the first internal layer, of an HDPE, or includes an HDPE in a fraction in a range from 45 to 90 wt %, based on the total weight of the first internal layer, and an LDPE in a fraction in a range from 10 to 55 wt %, based on the total weight of the first internal layer; b] a second internal layer which includes an LDPE in a fraction in a range from 90 to 100 wt %, based on the total weight of the second internal layer; and c] a third internal layer which includes an mPE in a fraction in a range from 10 to 50 wt %, based on the total weight of the third internal layer, and an LDPE in a fraction in a range from 50 to 90 wt %, based on the total weight of the third internal layer.

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. A process including as process steps A) providing the laminate according to claim 1, including a first longitudinal edge and a further longitudinal edge; B) folding the laminate; and C) contacting and joining the first longitudinal edge to the further longitudinal edge thereby obtaining a longitudinal seam.

10. A closed container filled with a foodstuff comprising the laminate according to claim 1.

11. A process including as process steps a) providing i) a laminate precursor including as layers of a layer sequence, in a direction from an external side of the laminate precursor to an internal side of the laminate precursor, I) a carrier layer which includes one selected from the group consisting of cardboard, paperboard, paper and a combination of at least two thereof, and II) a barrier layer, ii) a first polymer composition, iii) a second polymer composition, and iv) a third polymer composition; b) superimposing the barrier layer, on a side of the barrier layer that is facing away from the carrier layer, in a direction from the barrier layer to the internal side, with i) the first polymer composition, thereby obtaining a first internal layer which consists to an extent of 100 wt %, based on the total weight of the first internal layer, of an HDPE, ii) the second polymer composition, thereby obtaining a second internal layer which includes an LDPE in a fraction in a range from 90 to 100 wt %, based on the total weight of the second internal layer, and iii) the third polymer composition, thereby obtaining a third internal layer which includes an mPE in a fraction in a range from 10 to 50 wt %, based on the total weight of the third internal layer, and an LDPE in a fraction in a range from 50 to 90 wt %, based on the total weight of the third internal layer; where a polymeric internal layer of the laminate has a density in the range from 0.890 g/cm.sup.3 to 0.980 g/cm.sup.3 and includes the first internal layer, the second internal layer and the third internal layer as sublayers, where a graph of a differential scanning calorimetry of the polymeric internal 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.

12. The process according to claim 11, where the first polymer composition in process step b) is characterized by a melt flow index in a range from 2 to 14 g/10 min.

13. A process including as process steps a) providing i) a laminate precursor including as layers of a layer sequence, in a direction from an external side of the laminate precursor to an internal side of the laminate precursor, I) a carrier layer which includes one selected from the group consisting of cardboard, paperboard, paper, and a combination of at least two thereof, and II) a barrier layer, ii) a first polymer composition, iii) a second polymer composition, and iv) a third polymer composition; b) superimposing the barrier layer, on a side of the barrier layer that is facing away from the carrier layer, in a direction from the barrier layer to the internal side, with i) the first polymer composition, thereby obtaining a first internal layer which includes an HDPE in a fraction in a range from 45 to 90 wt %, based on the total weight of the first internal layer, and an LDPE in a fraction in a range from 10 to 55 wt %, based on the total weight of the first internal layer, ii) the second polymer composition, thereby obtaining a second internal layer which includes an LDPE in a fraction in a range from 90 to 100 wt %, based on the total weight of the second internal layer, and iii) the third polymer composition, thereby obtaining a third internal layer which includes an mPE in a fraction in a range from 10 to 50 wt %, based on the total weight of the third internal layer, and an LDPE in a fraction in a range from 50 to 90 wt %, based on the total weight of the third internal layer; where a polymeric internal layer of the laminate has a density in the range from 0.890 g/cm.sup.3 to 0.980 g/cm.sup.3 and includes the first internal layer, the second internal layer and the third internal layer as sublayers, where a graph of a differential scanning calorimetry of the polymeric internal 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.

14. The process according to claim 13, where the first polymer composition in process step b) is characterized by a melt flow index in a range from 2 to 14 g/10 min.

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 internal 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;

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

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

(11) 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, a colour layer 108, a polymeric external layer 107 of PE, a carrier layer 106 of cardboard, a further polymeric 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 internal layer 103 is shown in FIG. 2. 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 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 109 of 75 wt % HDPE and 25 wt % LDPE, based in each case on the total weight of the first internal layer 109; a second internal layer 110 of 100 wt % LDPE, based on the total weight of the second internal layer 110; and a third internal layer 111 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 111.

(12) FIG. 2 shows a schematic graph 201 of a differential scanning calorimetry measurement of the polymeric internal layer 103 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 B is 23 J/g. Definitions of the terms used are found, as also indicated above, in DIN EN ISO 11357-1:2010-03.

(13) FIG. 3 shows a container precurser 300 of the invention. The container precurser 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 precurser 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 precurser 300 includes a hole 305 in the carrier layer 106. The hole 305 is covered by the further polymeric 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 precurser 300, a closed container 400 is obtainable. A closed container 400 of this kind is shown in FIG. 4.

(14) FIG. 4 shows a closed container 400 of the invention. The closed container 400 is produced from the container precurser 300 according to FIG. 3. The closed container 400 comprises 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.

(15) 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 sheet-like composite precursor, including as layers of a layer sequence, in a direction from an external side 101 of the sheet-like composite precursor to an internal side 102 of the sheet-like composite precursor, a carrier layer 106 and a barrier layer 104. Furthermore, in process step a) 501, a first polymer composition, a second polymer composition and a third polymer composition are provided. The first polymer composition has a melt flow index of 4 g/10 min. The second polymer composition has a melt flow index of 7 g/10 min. The third polymer composition has a melt flow index of 7 g/10 min. In process step b) 502, the barrier layer 104, on a side of the barrier layer 104 that is facing away from the carrier layer 106, in a direction from the barrier layer 104 to the internal side 101, is superimposed by coextrusion with the first polymer composition thereby obtaining a first internal layer 109, with the second polymer composition thereby obtaining a second internal layer 110, and with the third polymer composition thereby obtaining a third internal layer 111. In this case, the first polymer composition is applied at a weight per unit area of 5 g/m.sup.2, the second polymer composition at a weight per unit area of 7 g/m.sup.2, and the third polymer composition at a weight per unit area of 10 g/m.sup.2. The first polymer composition consists of 75 wt % HDPE and 25 wt % LDPE, based in each case on the total weight of the first polymer composition. The second polymer composition consists of 100 wt % of LDPE, based on the total weight of the second polymer composition. The third polymer composition consists 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 polymer composition.

(16) 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 precurser 300 of FIG. 3 is produced according to the above description.

(17) 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 precurser 300 of FIG. 3 is provided. In a process step b. 702, a base region 304 of the container precurser 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 precurser 300 is filled with a foodstuff 401, and in a process step e. 705 the container precurser 300 is closed in a top region 303 by sealing, thereby obtaining the closed container 400. In a process step f. 706, the closed container 400 is joined to an opening aid 402.

(18) FIG. 8 shows a graph 201 of a differential scanning calorimetry measurement of a polymeric internal layer 103 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, a colour layer 108, a polymeric external layer 107 of PE, a carrier layer 106 of cardboard, a further polymeric layer 105 as laminating layer, a barrier layer 104 of aluminium, and the polymeric internal layer 103. The polymeric internal layer 103 includes an HDPE in a fraction of 65 wt % and an LDPE in a fraction of 35 wt %, based in each case on the total weight of the polymeric internal layer 103. 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.

(19) Also to be seen in FIG. 8 are a peak A at a temperature T.sub.A=102.53° C. and a peak B at a temperature T.sub.B=125.70° 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 92.45° C. and an extrapolated end temperature 206 of 109.19° C. Peak B is characterized by an extrapolated start temperature 207 of 121.24° C. and an extrapolated end temperature 208 of 129.26° 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.

(20) FIG. 9 shows a graph 201 of a differential scanning calorimetry measurement of a polymeric internal layer 103 of a further 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, a colour layer 108, a polymeric external layer 107 of PE, a carrier layer 106 of cardboard, a further polymeric layer 105 as laminating layer, a barrier layer 104 of aluminium, and the polymeric internal layer 103, which consists of 100 wt % of an HDPE, based on the total weight of the polymeric internal layer 103. 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. 9 are the heat flow dQ/dt in mW against the temperature T in ° C. Also to be seen in FIG. 9 are a peak A at a temperature T.sub.A=101.87° C. and a peak B at a temperature T.sub.B=126.03° C., in each case above a virtual interpolated baseline 801.

(21) 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 89.85° C. and an extrapolated end temperature 206 of 109.13° C. Peak B is characterized by an extrapolated start temperature 207 of 120.96° C. and an extrapolated end temperature 208 of 128.77° 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

(22) 100 sheet-like composite of the invention 101 external side 102 internal side 103 polymeric internal layer 104 barrier layer 105 further polymeric layer 106 carrier layer 107 polymeric external layer 108 colour layer 109 first internal layer 110 second internal layer 111 third internal 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