Sheet-like composite, especially packaging laminate for dimensionally stable foodstuff containers, having a polymeric intermediate layer characterized by differential scanning calorimetry
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 A and a peak B at a temperature T B , where the temperature TB is more than the temperature T 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.
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 A and a peak B at a temperature T B ,
where the temperature T B is more than the temperature T 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 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 A ,
where the peak B is characterized by an enthalpy of fusion H B ,
where a ratio of the enthalpy of fusion H A to the enthalpy of fusion H 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 B and the temperature T A is at least 10° C.
5 . The laminate according to claim 1 , where an absolute value of a difference between the temperature T B and the temperature T 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 A and a peak B at a temperature T B ,
where the temperature T B is more than the temperature T 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.