(CO)POLYESTER RESINS FOR USE AS HEAT SEAL LAYERS FOR CONTAINERS AND FILMS INCORPORATING SUCH LAYERS TO SEAL AND RESEAL CONTAINERS

1 . A composition comprising:

a (co)polyester resin comprising the reaction product of at least one diol and at least one diacid or diester and having a heat of fusion of 0.1 to 8 J/g, preferably 0.2 to 5 J/g, most preferably 0.5 to 3 J/g and a glass transition temperature between about 50° C. and 100° C., preferably between about 60° C. and about 90° C., and most preferably between about 65° C. and about 85° C.; and

an antifog agent;

wherein the composition has a heat of fusion of greater than the heat of fusion of the (co)polyester resin and a glass transition temperature less than the glass transition temperature of the (co)polyester resin.

2 . The composition of claim 1 , wherein the heat of fusion of the composition is 7.5 to 30 J/g, preferably 10 to 25 J/g, most preferably 12.5 to 20 J/g.

3 . The composition of claim 1 , wherein the glass transition temperature of the composition is between about 40° C. and 80° C., preferably between about 45° C. and about 75° C., and most preferably between about 50° C. and about 70° C.

4 . The composition of claim 1 , wherein the value of the melt peak of the (co)polyester resin is substantially the same as the value of the melt peak of the composition.

5 . The composition of claim 1 , wherein the at least one diacid or diester is mostly, substantially all, or all aromatic, and preferably is dimethylterephthalate, terephthalic acid, or blends thereof.

6 . The composition of claim 1 , wherein the at least two diacids or diesters are mostly, substantially all, or all aromatic and preferably comprise, consist essentially of, or consist of dimethyl terephthalate and isophthalic acid.

7 . The composition of claim 6 , wherein the at least two diacids or diesters consist of dimethyl terephthalate and isophthalic acid in a molar ratio of greater than 60:40, preferably between about 65:35 and about 95:5, and most preferably between about 70:30 and about 90:10.

8 . The composition of claim 1 , wherein the at least one diol is mostly, substantially all, or all aliphatic or cycloaliphatic and preferably comprises, consists essentially of, or consists of ethylene glycol.

9 . The composition of claim 1 , wherein the antifog agent is selected from the group consisting of a sorbitan ester, a glycerol ester, and blends thereof.

10 . A laminate comprising:

a heat seal layer comprising the composition of claim 1 ;

optionally, a pressure sensitive adhesive layer adhered to and in direct contact with the heat seal layer; and

a core layer adhered to the pressure sensitive adhesive layer when present or to the heat seal layer when the pressure sensitive adhesive layer is not present.

11 . The laminate of claim 10 , wherein the pressure sensitive adhesive layer is present and comprises a hot-melt self-adhesive composition which has a melt flow index, measured for a temperature of 190° C. using a weight of 2.16 kg, ranging from 0.01 to 200 g/10 minutes and which comprises:

from about 40% to about 70% by weight of a styrene block copolymer comprising at least one elastomer block, said styrene block copolymer comprising:

from about 30% to about 90% by weight of at least one diblock copolymer chosen from the group comprising SI, SBI, SIB, SB, SEB and SEP, and

from about 10% to about 70% by weight of at least one triblock copolymer chosen from the group comprising SIS, SIBS, SBS, SEBS and SEPS;

the total content of styrene units of said styrene block copolymer ranging from about 10% to about 40%; and

from about 30% to about 60% by weight of one or more tackifying resins having a softening temperature of between 5 and 140° C.

12 . A method of sealing a container comprising the steps of:

forming a laminate comprising a core layer and a heat seal layer comprising the composition of claim 1 ; and

heat sealing the laminate to the container.

13 . A method of forming a bag comprising the steps of:

forming a laminate comprising a core layer and a heat seal layer comprising the composition of claim 1 ; and

heat sealing the heat seal layer to itself.

14 . A package comprising a container; and

a lidding laminate comprising:

a heat seal layer adhered to the container and comprising the composition of claim 1 ;

optionally, a pressure sensitive adhesive layer adhered to and in direct contact with the heat seal layer; and

a core layer adhered to the pressure sensitive adhesive layer when present or to the heat seal layer when the pressure sensitive adhesive layer is not present.

15 . The package of claim 15 , wherein the pressure sensitive adhesive layer is present and the laminate has a reseal peel strength re-tack peel strength of at least about 0.5 N/15 mm, preferably at least about 0.7 but at most about 5 N/15 mm, preferably at most about 3 N/15 mm, tested after the third cycle of opening and re-sealing.