Heatsealable filter materials

1. Filter material comprising:

heat sealable, biodegradable and compostable polymeric fibers formed from a mixture of a biodegradable polymer and from 0.5 to 5.0% a by weight of a lubricant selected from the group consisting of fatty acid esters having a chain length of from 10 to 40 carbon atoms, based on the weight of the filter material, wherein the polymeric fibers have an increased fraction of crystalline zones.

2. Filter material according to claim 1 , wherein the heatsealable, biodegradable and compostable polymeric fibers are prepared from biodegradable polymers selected from the group consisting of:

(1) at least one aliphatic or partly aromatic polyester selected from:

A) aliphatic bifunctional alcohols; cycloaliphatic bifunctional alcohols; monomeric or oligomeric polyols based on ethylene glycol, propylene glycol, tetrahydrofuran or copolymers thereof having molecular weights up to 4000; branched bifunctional alcohols; multi-functional alcohols; aliphatic bifunctional acids; aromatic bifunctional acids; and multi-functional acids;

B) acid- and alcohol-functionalized building blocks or derivatives thereof;

(2) a mixture or a copolymer containing (A) and (B), wherein the aromatic acids do not account for more than a 50% by weight fraction, based on all acids present;

(3) at least one aliphatic or partly aromatic polyesteramide selected from:

C) aliphatic bifunctional alcohols; cycloaliphatic bifunctional alcohols; monomeric or oligomeric polyols based on ethylene glycol, propylene glycol, tetrahydrofuran or copolymers thereof having molecular weights up to 4000; branched bifunctional alcohols; multi-functional alcohols; aliphatic bifunctional acids; aromatic bifunctional acids; and multi-functional acids;

D) acid- and alcohol-functionalized building blocks, or derivatives thereof;

(4) a mixture or a copolymer containing (C) and (D), wherein the aromatic acids do not account for more than a 50% a by weight fraction, based on all acids present;

E) with an amide fraction from aliphatic and/or bifunctional amines, cycloaliphatic bifunctional and/or amines and branched bifunctional amines, and/or multi-functional amines; linear and/or cycloaliphatic bifunctional acids; branched bifunctional and/or aromatic bifunctional acids; and multi-functional acids;

F) with an amide fraction of acid- and amine-functionalized building blocks; and

(5) a mixture containing (C),(D),(E) and (F) wherein ester fraction (C) and (D) is at least 20% by weight.

3. Filter material according to claim 1 , wherein the filter material further comprises natural fibers.

4. Filter material according to claim 3 , wherein said filter material comprises at least two plies wherein at least one of said at least two plies contains said natural fibers and at least one of said two plies contains said biodegradable compostable fibers and said lubricant, and wherein said at least two plies are able to at least partially interpenetrate each other.

5. Filter material according to claim 3 , wherein the at least one of said at least one of said at least two plies containing said natural fibers has a basis weight between 8 and 40 g/m 2 and a DIN ISO 9237 air permeability from 300 to 4000 1/m 2 ·s.

6. Filter material according to claim 4 , wherein the at least one of said at least two plies containing the biodegradable compostable fibers has a basis weight from 1 to 15 g/m 2 .

7. Filter material according to claim 1 , wherein said at least one of said at least two plies containing natural fibers is constructed as a first ply and has a wet strength.

8. A filter material according to one of claims 1 , 6 , or 7 constructed and arranged as a tea bag, coffee bag, tea filter or coffee filter.