Dual shell dental appliance and material constructions
Improved dental appliances and polymeric sheet compositions are disclosed. The polymeric sheet compositions are useful for making dental appliances having outer layers comprised of a material having a modulus of from about 1,000 MPA to 2,500 MPA (“hard”) and an inner core comprised of elastomeric material or materials having a modulus of from about 50 MPa to 500 MPa (“soft”), which exhibit improved flexibility and strength, and better stain and tear resistance than currently available materials and dental appliances.
1. A polymeric sheet composition, comprising:
at least two outer layers and a middle layer B, wherein the A and C layers individually comprise a thermoplastic polymer having a flexural modulus of from about 1,000 MPa to 2,500 MPa and a glass transition temperature and/or melting point of from about 80° C. to 180° C. and the middle layer B is comprised of a polyurethane elastomer having a flexural modulus of from about 50 MPa to about 500 MPa and one or more of a glass transition temperature and/or melting point of from about 90° C. to about 220° C., wherein the polymeric sheet composition has a combined thickness of the A, B and C layers of from 250 microns to 2,000 microns and a flexural modulus of from 500 MPa to 1,500 MPa.
2. The composition of claim 1 , wherein the A and C layers are comprised of one of more of a co-polyester, a polycarbonate, a polyester polycarbonate blend, a polyurethane, a polyamide or a polyolefin.
3. The composition of claim 2 , wherein the middle layer B material has a Shore hardness of from A90 to D55 and a compression set of less than 35% after 22 hours at 25° C.
4. The composition of claim 3 , wherein the A and C layers have a lateral restoring force of less than 100 N (Newtons) per cm 2 when displaced by 0.05 mm to 0.1 mm relative to each other.
5. The composition of claim 3 , wherein the interlayer peel strength between the A and C layers and the B layer is greater than 50 N per 2.5 cm.
6. The composition of claim 3 , wherein the combined thickness of the A and C layers is from 50 microns to 1,000 microns.
7. The composition of claim 2 , wherein one or more of the A and C layers comprise a microcrystalline polyamide comprised of from 50 to 100 mole % of C6 to C14 aliphatic diacid moieties, and about 50 to 100 mole % of 4,4′-methylene-bis(cyclohexylamine), having a glass transition of between about 100° C. and 180° C., a heat of fusion of less than 20 J/g and a light transmission of greater than 80%.
8. The composition of claim 2 , wherein one or more of the A and C layers comprises a co-polyester comprised of:
(a) a dicarboxylic acid component comprising 70 mole % to 100 mole % of terephthalic acid residues, and
(b) a diol component comprising
(i) 0 to 95 mole % ethylene glycol,
(ii) 5 mole % to 50 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues,
(iii) 50 mole % to 95 mole % 1,4-cyclohexanedimethanol residues, and
(iv) 0 to 1 mole % of a polyol having three or more hydroxyl groups,
wherein the sum of the mole % of diol residues (i), (ii), (iii) and (iv) amounts to 100 mole % and the copolyester exhibits a glass transition temperature Tg from 80° C. to 150° C.
9. The composition of claim 8 , wherein the middle layer B comprises an aromatic polyether polyurethane having a Shore hardness of from A90 to D55 and a compression set of less than 35%, wherein the interlayer peel strength between the A and C layers and the B layer is greater than 50 N per 2.5 cm.
10. The composition of claim 2 , wherein one or more of the A and C layers comprises a polyurethane comprised of:
(a) a di-isocyanate comprising 80 mole % to 100 mole % of methylene diphenyl diisocyanate residues and/or hydrogenated methylene diphenyl diisocyanate, and
(b) a diol component comprising
(i) 0 to 100 mole % hexamethylene diol
(ii) 0 to 50 mole % 1,4-cyclohexanedimethanol
wherein the sum of (i) and (ii) amounts to greater than 90 mole % and the polyurethane has a glass transition temperature Tg from about 85° C. to about 150° C.
11. A dental appliance conformal to one or more teeth comprising a composition according to claim 4 .
12. A dental appliance conformal to one or more teeth, comprising a composition according to claim 8 .
13. A dental appliance conformal to one or more teeth, comprising a composition according to claim 9 .
14. The dental appliance conformal of claim 13 , wherein the elastomeric middle layer and the outer layers reversibly move relative to each other and have a lateral restoring force of less than 100 N per cm 2 when displaced by 0.05 mm to 0.1 mm relative to each other, wherein the dental appliance conformal is reversibly deformable.
15. A polymeric sheet composition comprised of at least two outer layers A and C and an elastomeric middle layer B, wherein one or both of the outer layers is a polyester or co-polyester having a flexural modulus of from about 1,000 MPa to 2,500 MPa and the middle layer B is a polyurethane elastomer having a flexural modulus of from about 50 MPa to about 500 MPa, wherein the inter layer peel strength between at least one outer layer and the middle layer B is greater than about 50 N per 2.5 cm, wherein the polymeric sheet composition has a combined thickness of the A, B and C layers of from 250 microns to 2,000 microns and a flexural modulus of from 500 MPa to 1,500 MPa.
16. The polymeric sheet composition according to claim 15 , wherein the middle layer B comprises an aromatic polyether polyurethane having a Shore hardness of from about A90 to D55 and a compression set of less than 35%.
17. The polymeric sheet composition according to claim 15 , wherein the polymeric sheet composition has improved environmental stress resistance relative to an A or C layer alone.
18. The polymeric sheet composition according to claim 15 , wherein the polymeric sheet composition has improved tear resistance relative to an A or C layer alone.
19. The polymeric sheet composition according to claim 15 , wherein the polymeric sheet composition has improved impact strength relative to an A or C layer alone.
20. A dental appliance comprising a polymeric sheet, said polymeric sheet comprised of at least two outer layers A and C and an elastomeric middle layer B, wherein one or more of the outer layers is a polyester or co-polyester having a modulus of from about 1,000 MPa to 2,500 MPa and the inner layer is a polyurethane elastomer having a modulus of from about 50 MPa to about 500 MPa, wherein the inter layer peel strength between at least one outer layer and the middle B layer is greater than about 50 N per 2.5 cm.
21. The dental appliance according to claim 20 , wherein the dental appliance exhibits improved stain resistance relative to an A or C layer alone.
22. A polymeric sheet composition, comprising:
at least two outer layers A and C and a middle layer B, wherein the A and C layers individually comprise a thermoplastic polymer having a modulus of from about 1,000 MPa to 2,500 MPa and a glass transition temperature and/or melting point of from about 80° C. to 180° C. and the middle layer B is comprised of a polyurethane elastomer having a modulus of from about 50 MPa to about 500 MPa and one or more of a glass transition temperature and/or melting point of from about 90° C. to about 220° C., wherein one or more of the A and C layers comprise a microcrystalline polyamide comprised of from 50 to 100 mole % of C6 to C14 aliphatic diacid moieties, and about 50 to 100 mole % of 4,4′-methylene-bis(cyclohexylamine), having a glass transition of between about 100° C. and 180° C., a heat of fusion of less than 20 J/g and a light transmission of greater than 80%.
23. A polymeric sheet composition, comprising:
at least two outer layers A and C and a middle layer B, wherein the A and C layers individually comprise a thermoplastic polymer having a modulus of from about 1,000 MPa to 2,500 MPa and a glass transition temperature and/or melting point of from about 80° C. to 180° C. and the middle layer B is comprised of a polyurethane elastomer having a modulus of from about 50 MPa to about 500 MPa and one or more of a glass transition temperature and/or melting point of from about 90° C. to about 220° C., wherein one or more of the A and C layers comprises a co-polyester comprised of:
(a) a dicarboxylic acid component comprising 70 mole % to 100 mole % of terephthalic acid residues, and
(b) a diol component comprising
(i) 0 to 95 mole % ethylene glycol,
(ii) 5 mole % to 50 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues,
(iii) 50 mole % to 95 mole % 1,4-cyclohexanedimethanol residues, and
(iv) 0 to 1 mole % of a polyol having three or more hydroxyl groups,
wherein the sum of the mole % of diol residues (i), (ii), (iii) and (iv) amounts to 100 mole % and the copolyester exhibits a glass transition temperature Tg from 80° C. to 150° C.
24. The composition of claim 23 , wherein the middle layer B comprises an aromatic polyether polyurethane having a Shore hardness of from A90 to D55 and a compression set of less than 35%, wherein the interlayer peel strength between the A and C layers and the middle layer B is greater than 50 N per 2.5 cm.
25. A polymeric sheet composition, comprising:
at least two outer layers A and C and a middle layer B, wherein the A and C layers individually comprise a thermoplastic polymer having a modulus of from about 1,000 MPa to 2,500 MPa and a glass transition temperature and/or melting point of from about 80° C. to 180° C. and the middle layer B is comprised of a polyurethane elastomer having a modulus of from about 50 MPa to about 500 MPa and one or more of a glass transition temperature and/or melting point of from about 90° C. to about 220° C., wherein one or more of the A and C layers comprises a polyurethane comprised of:
(a) a di-isocyanate comprising 80 mole % to 100 mole % of methylene diphenyl diisocyanate residues and/or hydrogenated methylene diphenyl diisocyanate, and
(b) a diol component comprising
(i) 0 to 100 mole % hexamethylene diol
(ii) 0 to 50 mole % 1,4-cyclohexanedimethanol
wherein the sum of (i) and (ii) amounts to greater than 90 mole % and the polyurethane has a glass transition temperature Tg from about 85° C. to about 150° C.