Fluorescent glazing composition for a dental zirconia article, process of sintering and kit of parts

1. A glazing composition for a porous dental zirconia article, the glazing composition comprising

liquid,

glass particles present in an amount of 5 wt % to 40 wt % with respect to the weight of the glazing composition,

wherein if the glass particles comprise Li 2 O, the Li 2 O is present in an amount of no more than 0.1 mol %,

fluorescing component(s) comprising europium,

wherein the fluorescing component(s) can be contained in the glass particles or as separate component,

optionally hydrophilic silica nano-particles, and

optionally hydrophobic silica nano-particles.

2. The glazing composition according to claim 1 , the ratio of glass particles to europium being in a range of 1,000:1 to 20:1 with respect to weight.

3. The glazing composition according to claim 1 , the liquid selected from water, alcohols, polyols, and a combination thereof.

4. The glazing composition according to claim 1 , the glass particles comprising one or more of the following compositions:

1

2

3

4

5

6

7

SiO 2

80 to 98

80 to 98

80 to 98

80 to 98

80 to 98

85 to

80 to

98

98

B 2 O 3

0 to 15

0 to 15

2 to 15

2 to 15

Na 2 O

0 to 5

0 to 5

K 2 O

0 to 5

0 to 5

0.1 to 5

0.1 to 5

5 to 10

Al 2 O 3

0 to 5

0 to 5

0.1 to 5

0.1 to 5

0.1 to 5

8 to 12

La 2 O 3

0 to 1

0 to 1

MgO

0 to 5

0 to 5

0.1 to 5

0.1 to 5

CaO

0 to 2

0 to 2

SrO

0 to 2

0 to 2

BaO

0 to 2

0 to 2

Bi 2 O 3

0 to 0.5

0 to 0.5

Eu 2 O 3

0 to 1

0.05 to 1

0 to 1

wherein the amounts are given in mol %.

5. The glazing composition according to claim 4 , the glass particles being characterized by one or more of:

viscosity: at least 10 4 Pa*s at a temperature of 1,300° C.;

coefficient of thermal expansion: 1*10 −6 K −1 to 10*10 −6 K −1 ;

surface tension: of 210 to 300 mN/m at 1,300° C.;

Littleton softening point viscosity at a temperature of 1,100° C. to 1,350° C.;

flow point viscosity at a temperature of 1,300° C. to 1,650° C.; and

particle size (D 50 ): 1 to 40 μm,

wt. % with respect to the weight of the glazing composition.

6. The glazing composition according to claim 1 , the fluorescing component(s) characterized by one or more of:

being present in an amount of 0.1 to 5 wt. % with respect to the weight of the whole composition calculated with respect to the amount of europium;

particle size (D 50 ): 1 to 40 μm; and

being selected from oxides, hydroxides or carbonates of Eu.

7. The glazing composition according to claim 1 , comprising:

the liquid present in an amount of 50 to 95 wt. %,

the fluorescing component(s) present in an amount of 0.1 to 5 wt. % calculated with respect to the amount of europium,

the hydrophilic silica nano-particles present in an amount of 0 to 5 wt. %, and

the hydrophobic silica nano-particles present in an amount of 0 to 5 wt. %; and further comprising:

a rheological additive present in an amount of 0 to 1 wt. %,

an organic colorant present in an amount of 0 to 0.5 wt. %,

wt. % with respect to the weight of the glazing composition.

8. The glazing composition according to claim 1 , comprising hydrophilic silica nano-particles, the hydrophilic silica nano-particles being characterized by one or more of:

particle size (D 50 ): 10 to 70 nm;

BET surface: 20 to 500 m 2 /g; and

being present in an amount of 0.1 to 5 wt. %,

wt. % with respect to the weight of the glazing composition.

9. The glazing composition according to claim 1 , being characterized by one or more of:

viscosity: 10 to 2,500 mPa*s at 23° C.; and

pH value: 6 to 9.

10. The glazing composition according to claim 1 , wherein:

the liquid is selected from water, an alcohol, a polyol, and a combination thereof,

the liquid is present in an amount of 50 to 95 wt. %,

the glass particles are characterized by a particle size (D 50 ) of 1 to 40 μm

the glass particles characterized by a viscosity of 10 4 to 10 7 Pa*s at 1,300° C.,

the fluorescing component(s) is present in an amount of 0.1 to 5 wt. % calculated with respect to the amount of europium,

the hydrophilic silica nano-particles are present in an amount of 0 to 5 wt. %, and

the hydrophobic silica nano-particles are present in an amount of 0 to 5 wt. %,

wt. % with respect to the weight of the glazing composition.

11. The glazing composition of claim 1 , the glass particles comprising SiO 2 in an amount of at least 80 wt %.

12. The glazing composition of claim 1 , the glass particles characterized by a particle size (D 50 ) of 1 to 40 μm.

13. The glazing composition of claim 1 , wherein the fluorescing component(s) comprising europium is europium oxide, the fluorescing component(s) comprising europium present in an amount of 0.1 to 5 wt. % calculated with respect to the weight of europium.

14. A glazing composition for a porous dental zirconia article, the glazing composition comprising

liquid,

glass particles comprising at least 80 wt. % SiO 2 ,

fluorescing component(s) comprising europium,

wherein the fluorescing component(s) can be contained in the glass particles or as separate component,

optionally hydrophilic silica nano-particles, and

optionally hydrophobic silica nano-particles.

15. A process of producing a dental zirconia article, the process comprising:

providing a porous dental zirconia article,

applying the glazing composition according to claim 1 to at least a part of a surface of the porous dental zirconia article, and

sintering the porous dental zirconia article with the glazing composition on the surface to final density.

16. The process according to claim 15 , the porous dental zirconia article being characterized by one or more of:

biaxial flexural strength: 15 to 55 determined according to ISO 6872:2015; and

Vickers hardness: 15 to 150 (HV 0.5).

17. The process according to claim 15 , the sintering comprising regular sintering or fast sintering,

the regular sintering comprising one or more of:

sintering temperature: 1,350 to 1,600° C.;

duration: 50 to 360 min; and

heating rate: 1 to 30° C./min;

the fast sintering comprising one or more of:

sintering temperature: 1,450 to 1,600° C.;

duration: 10 to 40 min; and

heating rate: 60 to 420° C./min.

18. A kit of parts comprising:

the glazing composition according to claim 1 ; and

a dental zirconia mill blank suitable for producing a dental restoration.

19. The kit of claim 18 , further comprising one or more of:

sintering aids,

application device for the surface treating agent,

a shade guide,

polishing aids, and

a sintering oven.