Indian Patents. 270999:A PROCESS FOR FUNCTIONALIZING TITANIUM METAL SURFACES WITH NANOMETRIC PARTICLES OF TITANIUM AND PRODUCTS THUS FUNCTIONALIZED

Title of Invention	A PROCESS FOR FUNCTIONALIZING TITANIUM METAL SURFACES WITH NANOMETRIC PARTICLES OF TITANIUM AND PRODUCTS THUS FUNCTIONALIZED
Abstract	A method is described which enables antibacterial properties to be attributed to a titanium surface by applying titanium dioxide suspensions of anemometrical dimensions .

Full Text	A PROCESS FOR TITANIUM METAL SURFACES WITH NANOMETRIC PARTICLES OF TITANIUM AND PRODUCTS THUS FUNCTIONALIZED Field of the invention The present invention relates to the field of titanium metal surface treatment. State of tile art In recent times titanium has been widely utilized in the manufacture of parts used in implantology (particularly in the orthodontic field). In view of this use, the ability of the surfaces of the various constituent parts of such implants to perform a bactericidal and/or bacteriostatic action is evidently important. Italian patent application FI2004A000252 (in the name of the same applicant) describes a process for preparing titanium oxide in nanoparticle form and the relative dispersions obtained by said process, consisting of nanometric particles of titanium oxide suspended in a mixture of water and a suitable complexing solvent (such as polyethylene glycol). The aforesaid patent application also mentions the usefulness of said suspensions for preparing photocatalytic coatings. Similarly, Italian patent FI2006A000030 describes a process for preparing titanium oxide in nanoparticle form in an aqueous dispersion and the relative dispersions themselves. Summary of the invention The present invention refers to a process for functionalizing titanium metal surfaces with nanometric particles of titanium wherein: - the article to be functionalized is immersed in a suspension of nanometric particles of titanium dioxide; - when completely wetted the article is heated to remove the solvent; - the article is subjected to a thermal cycle in order to improve fixing of the nanoparticles to the treated surface. Detailed description of the invention it has now been surprisingly found that dispersions of nanometric particles of titanium oxide as described in the aforesaid patent applications lend themselves in particular to the treatment of titanium surfaces, enabling them to exert a bactericidal or bacteriostatic action which is found to be extremely useful and interesting in the case of prostheses, or parts thereof, particularly orthodontic parts formed of this metal. As is more amply illustrated in patent application FI2004A000252 the process for preparing dispersions of anatase TiOa particles usable in the present invention, comprises the following stages: i) reacting a titanium alkoxide with a suitable complexing solvent; ii) distilling the solution derived from step i) until a small quantity results; iii) adding water together with said complexing solvent and one or more polycondensation inhibitors to the solution derived from step ii), then heating the reaction mixture under reflux, to obtain the desired nanoparticulate dispersion. The titanium alkoxide is preferably chosen from the group consisting of titanium methoxide, ethoxide, normal-propoxide, isopropoxide, normal-butoxide, and isobutoxide, being preferably titanium isopropoxide. The complexing solvents typically used in the present process are polyethylene glycols, having molecular weights for example of between 200 and 600. Longer chain polyethylene glycols of molecular weight up to 10,000 can also be used, diethylene glycol being preferred. The term "polycondensation inhibitor" means typically a mixture comprising at least one mineral acid and one organic acid, where the mineral acid can be chosen for example from the group consisting of hydrochloric acid, nitric acid, sulfuric acid, perchloric acid, hydrobromic acid and hydriodic acid, and the organic acid is preferably acetic acid; the polycondensation inhibitor is preferably a mixture of hydrochloric acid and acetic acid. The quantity of polycondensation inhibitor added is such that the mineral acid quantity is between 0.1 and 10% by volume on the total volume of the reaction mixture, while the organic acid quantity is between 1 and 20% by volume on the total volume of the reaction mixture. The aforesaid patent application FI2006A000Q30 also amply illustrates and claims a process for preparing dispersions of anatase TiOa particles in water. According to this process a titanium salt is reacted in water under hot conditions in the presence of mineral acids and a non-ionic surfactant, the solution thus obtained being then possibly reduced to a small quantity. Both the general and preferred definitions of titanium salt and mineral acid, already aforegiven for the process of patent application FI2004A00025, are valid, whereas "non-ionic surfactants" mean those possessing an ether or ester type polar function, being preferably Triton X-1 GO (TX-1 GO). The molar ratio of titanium alkoxide to acid is between 0.005 and 15, preferably between 5 and 6, while the reaction temperature is normally between 15 and 95°C preferably 45-55°C^and the reaction times are between 12 and 72 hours, being preferably 24 hours. Furthermore, as described in both applications, in both the above cases Ti can be doped with a metal chosen from the transition metal series and particularly from Ag, Cu and Ce by the addition a salt thereto in step i) or alternatively in step iii) of the present process. In this manner, the process will lead to the formation of a TiOa dispersion doped with Ag, Cu or Ce, able to exhibit its own catalytic activity even without UV light irradiation. An illustrative example for preparing the suspensions used in the present invention both comprising the complexing agent and in aqueous suspension (examples already given in the aforesaid patent applications) are given hereinafter. EXAMPLES Preparation of a nanoparticulate dispersion of anatase TiO? in water/diethylene glycol starting from Ti isopropoxide Example 1 5.53 litres of diethylene glycol are fed into a 20 litre flask to which are added 5.54 litres of titanium isopropoxide. The reaction mixture is maintained under agitation for 5 minutes then heated to 120°C to distil off the isopropyl alcohol formed, until a small quantity results. 11.1 litres of diethylene glycol, 125 ml of 32-33% hydrochloric acid (w/w), 2.07 litres of glacial acetic acid and 125 ml of deionized water are added; the temperature is brought to 180°C and the mixture maintained under reflux for 2 hours. Example 2 5 g of concentrated HCI, 75 g of TX-100 and water to make up to 750 g in weight are placed into a 2 litre reactor heated with circulating diathermic oil in an external jacket. The temperature is brought to 50°C. 50 g of Ti[OCH(CH3)2]4 (TIP) are then added very quickly and the formation of a white flocculate precipitate is immediately noted. After 7 hours a very stable transparent sol is formed. The suspensions thus obtained are then used to functionaiize the surface of titanium metal parts. In particular the article to be functionalized is immersed in the suspension and possibly rotated so as to completely wet the surface therewith. It is then heated and finally subjected to a thermal cycle in order to improve the fixing of nanoparticles onto the treated surface. The suspensions used for the initial bath generally contain from 0.1% to 15%, preferably 1%, of nanometric titanium dioxide, and possibly from 0.005% to 0.5%, preferably 0.05%, of silver, the percentages being calculated by weight on the solution. The sole function of the initial heating is to accelerate solvent removal and can be undertaken for example in an oven at around 120°C. The subsequent thermal cycle comprises an increasing temperature gradient between 0.1 and 10°C/minute starting from ambient temperature up to a temperature of between 400° and 850°C which is maintained for a time between 30 and 240 minutes, the treated article being allowed to cool 6ovm freely to ambient temperature. The process in accordance with the present invention can be undertaken on ground surfaces but, if preferred, the surface can be subjected to mordanting in accordance with normally employed techniques for this purpose, prior to immersion in the titanium dioxide suspension. Some examples are described hereinafter for treating a titanium article in accordance with the invention with the aim of attributing thereto the desired bactericidal properties. Example 3 A titanium screw for orthodontic implants was subjected to mordanting with mixtures of acids (a known process in the state of the art) in order to obtain a structured non-smooth surface. This was immersed into a formulated product in diethylene glycol containing 1% by weight of nanoparticulate titanium dioxide and kept under rotation for 5 seconds. The screw was then placed in an oven at 120°C for 1 hour in order to promote solvent evaporation. In this step the titanium dioxide nanoparticles deposit onto the surface of the screw. The screw is then treated at high temperature to stably fix the nanoparticles to the metal. The thermal cycle consists of a heating ramp up to 650°C lasting 2 hours, a plateau of 2 hours, then free cooling to ambient temperature. Example 4 A ground titanium screw for orthodontic implants was immersed in a formulated product in diethylene glycol containing nanoparticulate silver adsorbed onto nanoparticulate titanium dioxide for a total content of 1% of titanium dioxide and 0.05% of nanoparticulate silver and kept under rotation for 5 seconds. The scr-ew was then placed in an oven at 120°C for 1 hour in order to promote solvent evaporation. In this step the titanium dioxide nanoparticles deposit onto the surface of the screw. The screw is then treated at high temperature to stably fix the nanoparticles to the metal. The thermal cycle consists of a heating ramp up to 650°C lasting 2 hours, a plateau of 2 hours, then free cooling to ambient temperature. Example 5 A mordanted titanium screw for orthodontic implants was immersed in a formulated product in water containing nanoparticulate silver adsorbed onto nanoparticulate titanium dioxide for a total content of 0.1 % of titanium dioxide and 0.005% of nanoparticulate silver and kept under rotation for 5 seconds. The screw was then placed in an oven at 120°C for 1 hour in order to promote solvent evaporation. In this step the titanium dioxide nanoparticles deposit onto the surface of the screw. The screw is then treated at high temperature to stably fix the nanoparticles to the metal. The thermal cycle consists of a heating ramp up to 750°C lasting 2 hours, a plateau of 2 hours, then free cooling to ambient temperature. Example 6 An aqueous solution of nanoparticulate titanium dioxide containing 1% by weight of the oxide was sprayed onto one side of a small smooth titanium plate. The small plate is dried in an oven at 120°C for 1 hour in order to promote solvent evaporation. The small plate is then treated at high temperature to fix the nanoparticles to the metal. The thermal cycle consists of a heating ramp up to 800°C lasting 2 hours, a plateau of 2 hours, then free cooling to ambient temperature. MEW SET OF CLA!MS 1. A process for functionalizing titanium metal surfaces with nanometric particles of titanium therein: - the article to be functionalized Is immersed in a suspension of nanometric particles of titanium dioxide - when completely wetted the article is heated to remove the solvent; - the article is subjected to a thermal cycle. 2. A process as claimed In claim 1 wherein the surface is mordanted prior to immersing the article in the suspension of nanometric titanium dioxide, 3. A process as claimed in claims 1 and 2 wherein the suspensions used for the initial bath contain between 0.1% and 15% of nanometric titanium dioxide. 4. A process as claimed in claim 3 wherein the suspensions contain 1% of titanium dioxide. 5. A process as claimed in claims 1-4 wherein the suspensions contain between 0.005% and 0.5%, preferably 0.05%, of silver. 6. A process as claimed in claims 1-5 wherein said thermal cycle comprises: - a rising gradient of between 0.1 and 10°C/minute starting from ambient temperature up to a temperature of between 400° and 850°C; - maintaining the temperature attained for a period between 30 and 240 minutes; - free cooling to ambient temperature. 7. A process as claimed in claims 1-6 wherein said suspensions of nanometric titanium dioxide are obtained by a process comprising the following steps: i) reacting a titanium alkoxide with a suitable complexing solvent; ii) distilling the solution derived from step i); ill) adding water together with said complexing solvent and one or more polycondensation inhibitors to the solution derived from step it), then heating the reaction mixture under reflux to obtain the desired nanoparticulate dispersion. 8. A process as claimed in claims 1-6 wherein said suspensions of nanometric titanium dioxide are obtained by a process comprising the following steps: - reacting a titanium salt under hot conditions in water in the presence of mineral acids and a non-ionic surfactant; - possibly reducing the solution thus obtained to a small quantity. 9. metal surfaces coated with nanometric particles of titanium dioxide using the process claimed in claims 1-8. 10. Metal surfaces as claimed in claim 9 wherein said surfaces are those of prostheses, or parts thereof, for orthodontic applications. 11. Prostheses, or parts thereof, for orthodontic application, whose surfaces are coated with nanometric particles of titanium dioxide using the process claimed in claims 1-8.

Full Text

A PROCESS FOR TITANIUM METAL SURFACES WITH
NANOMETRIC PARTICLES OF TITANIUM AND PRODUCTS THUS
FUNCTIONALIZED
Field of the invention
The present invention relates to the field of titanium metal surface treatment.
State of tile art
In recent times titanium has been widely utilized in the manufacture of parts used
in implantology (particularly in the orthodontic field). In view of this use, the ability
of the surfaces of the various constituent parts of such implants to perform a
bactericidal and/or bacteriostatic action is evidently important.
Italian patent application FI2004A000252 (in the name of the same applicant)
describes a process for preparing titanium oxide in nanoparticle form and the
relative dispersions obtained by said process, consisting of nanometric particles of
titanium oxide suspended in a mixture of water and a suitable complexing solvent
(such as polyethylene glycol). The aforesaid patent application also mentions the
usefulness of said suspensions for preparing photocatalytic coatings.
Similarly, Italian patent FI2006A000030 describes a process for preparing titanium
oxide in nanoparticle form in an aqueous dispersion and the relative dispersions
themselves.
Summary of the invention
The present invention refers to a process for functionalizing titanium metal
surfaces with nanometric particles of titanium wherein:
- the article to be functionalized is immersed in a suspension of nanometric particles of titanium dioxide;
- when completely wetted the article is heated to remove the solvent;
- the article is subjected to a thermal cycle in order to improve fixing of the nanoparticles to the treated surface.
Detailed description of the invention
it has now been surprisingly found that dispersions of nanometric particles of titanium oxide as described in the aforesaid patent applications lend themselves in particular to the treatment of titanium surfaces, enabling them to exert a bactericidal or bacteriostatic action which is found to be extremely useful and

interesting in the case of prostheses, or parts thereof, particularly orthodontic parts
formed of this metal.
As is more amply illustrated in patent application FI2004A000252 the process for
preparing dispersions of anatase TiOa particles usable in the present invention,
comprises the following stages:
i) reacting a titanium alkoxide with a suitable complexing solvent;
ii) distilling the solution derived from step i) until a small quantity results;
iii) adding water together with said complexing solvent and one or more
polycondensation inhibitors to the solution derived from step ii), then heating the
reaction mixture under reflux, to obtain the desired nanoparticulate dispersion.
The titanium alkoxide is preferably chosen from the group consisting of titanium
methoxide, ethoxide, normal-propoxide, isopropoxide, normal-butoxide, and
isobutoxide, being preferably titanium isopropoxide.
The complexing solvents typically used in the present process are polyethylene
glycols, having molecular weights for example of between 200 and 600. Longer
chain polyethylene glycols of molecular weight up to 10,000 can also be used,
diethylene glycol being preferred.
The term "polycondensation inhibitor" means typically a mixture comprising at
least one mineral acid and one organic acid, where the mineral acid can be
chosen for example from the group consisting of hydrochloric acid, nitric acid,
sulfuric acid, perchloric acid, hydrobromic acid and hydriodic acid, and the organic
acid is preferably acetic acid; the polycondensation inhibitor is preferably a mixture
of hydrochloric acid and acetic acid.
The quantity of polycondensation inhibitor added is such that the mineral acid
quantity is between 0.1 and 10% by volume on the total volume of the reaction
mixture, while the organic acid quantity is between 1 and 20% by volume on the
total volume of the reaction mixture.
The aforesaid patent application FI2006A000Q30 also amply illustrates and claims
a process for preparing dispersions of anatase TiOa particles in water.
According to this process a titanium salt is reacted in water under hot conditions in
the presence of mineral acids and a non-ionic surfactant, the solution thus
obtained being then possibly reduced to a small quantity. Both the general and

preferred definitions of titanium salt and mineral acid, already aforegiven for the
process of patent application FI2004A00025, are valid, whereas "non-ionic
surfactants" mean those possessing an ether or ester type polar function, being
preferably Triton X-1 GO (TX-1 GO).
The molar ratio of titanium alkoxide to acid is between 0.005 and 15, preferably
between 5 and 6, while the reaction temperature is normally between 15 and 95°C
preferably 45-55°C^and the reaction times are between 12 and 72 hours, being
preferably 24 hours.
Furthermore, as described in both applications, in both the above cases Ti can be
doped with a metal chosen from the transition metal series and particularly from
Ag, Cu and Ce by the addition a salt thereto in step i) or alternatively in step iii) of
the present process. In this manner, the process will lead to the formation of a
TiOa dispersion doped with Ag, Cu or Ce, able to exhibit its own catalytic activity
even without UV light irradiation.
An illustrative example for preparing the suspensions used in the present
invention both comprising the complexing agent and in aqueous suspension
(examples already given in the aforesaid patent applications) are given
hereinafter.
EXAMPLES
Preparation of a nanoparticulate dispersion of anatase TiO? in water/diethylene
glycol starting from Ti isopropoxide
Example 1
5.53 litres of diethylene glycol are fed into a 20 litre flask to which are added 5.54
litres of titanium isopropoxide. The reaction mixture is maintained under agitation
for 5 minutes then heated to 120°C to distil off the isopropyl alcohol formed, until a
small quantity results. 11.1 litres of diethylene glycol, 125 ml of 32-33%
hydrochloric acid (w/w), 2.07 litres of glacial acetic acid and 125 ml of deionized
water are added; the temperature is brought to 180°C and the mixture maintained
under reflux for 2 hours.
Example 2
5 g of concentrated HCI, 75 g of TX-100 and water to make up to 750 g in weight
are placed into a 2 litre reactor heated with circulating diathermic oil in an external

jacket. The temperature is brought to 50°C. 50 g of Ti[OCH(CH3)2]4 (TIP) are
then added very quickly and the formation of a white flocculate precipitate is
immediately noted.
After 7 hours a very stable transparent sol is formed.
The suspensions thus obtained are then used to functionaiize the surface of
titanium metal parts.
In particular the article to be functionalized is immersed in the suspension and
possibly rotated so as to completely wet the surface therewith. It is then heated
and finally subjected to a thermal cycle in order to improve the fixing of
nanoparticles onto the treated surface.
The suspensions used for the initial bath generally contain from 0.1% to 15%,
preferably 1%, of nanometric titanium dioxide, and possibly from 0.005% to 0.5%,
preferably 0.05%, of silver, the percentages being calculated by weight on the
solution. The sole function of the initial heating is to accelerate solvent removal
and can be undertaken for example in an oven at around 120°C.
The subsequent thermal cycle comprises an increasing temperature gradient
between 0.1 and 10°C/minute starting from ambient temperature up to a
temperature of between 400° and 850°C which is maintained for a time between
30 and 240 minutes, the treated article being allowed to cool 6ovm freely to
ambient temperature.
The process in accordance with the present invention can be undertaken on
ground surfaces but, if preferred, the surface can be subjected to mordanting in
accordance with normally employed techniques for this purpose, prior to
immersion in the titanium dioxide suspension.
Some examples are described hereinafter for treating a titanium article in
accordance with the invention with the aim of attributing thereto the desired
bactericidal properties.
Example 3
A titanium screw for orthodontic implants was subjected to mordanting with
mixtures of acids (a known process in the state of the art) in order to obtain a
structured non-smooth surface. This was immersed into a formulated product in
diethylene glycol containing 1% by weight of nanoparticulate titanium dioxide and

kept under rotation for 5 seconds.
The screw was then placed in an oven at 120°C for 1 hour in order to promote
solvent evaporation. In this step the titanium dioxide nanoparticles deposit onto
the surface of the screw. The screw is then treated at high temperature to stably
fix the nanoparticles to the metal. The thermal cycle consists of a heating ramp
up to 650°C lasting 2 hours, a plateau of 2 hours, then free cooling to ambient
temperature.
Example 4
A ground titanium screw for orthodontic implants was immersed in a formulated
product in diethylene glycol containing nanoparticulate silver adsorbed onto
nanoparticulate titanium dioxide for a total content of 1% of titanium dioxide and
0.05% of nanoparticulate silver and kept under rotation for 5 seconds.
The scr-ew was then placed in an oven at 120°C for 1 hour in order to promote
solvent evaporation. In this step the titanium dioxide nanoparticles deposit onto
the surface of the screw. The screw is then treated at high temperature to stably
fix the nanoparticles to the metal. The thermal cycle consists of a heating ramp
up to 650°C lasting 2 hours, a plateau of 2 hours, then free cooling to ambient
temperature.
Example 5
A mordanted titanium screw for orthodontic implants was immersed in a
formulated product in water containing nanoparticulate silver adsorbed onto
nanoparticulate titanium dioxide for a total content of 0.1 % of titanium dioxide and
0.005% of nanoparticulate silver and kept under rotation for 5 seconds.
The screw was then placed in an oven at 120°C for 1 hour in order to promote
solvent evaporation. In this step the titanium dioxide nanoparticles deposit onto
the surface of the screw. The screw is then treated at high temperature to stably
fix the nanoparticles to the metal. The thermal cycle consists of a heating ramp
up to 750°C lasting 2 hours, a plateau of 2 hours, then free cooling to ambient
temperature.
Example 6
An aqueous solution of nanoparticulate titanium dioxide containing 1% by weight
of the oxide was sprayed onto one side of a small smooth titanium plate. The

small plate is dried in an oven at 120°C for 1 hour in order to promote solvent evaporation. The small plate is then treated at high temperature to fix the nanoparticles to the metal. The thermal cycle consists of a heating ramp up to 800°C lasting 2 hours, a plateau of 2 hours, then free cooling to ambient temperature.

MEW SET OF CLA!MS
1. A process for functionalizing titanium metal surfaces with nanometric particles
of titanium therein:
- the article to be functionalized Is immersed in a suspension of nanometric
particles of titanium dioxide
- when completely wetted the article is heated to remove the solvent;
- the article is subjected to a thermal cycle.

2. A process as claimed In claim 1 wherein the surface is mordanted prior to immersing the article in the suspension of nanometric titanium dioxide,
3. A process as claimed in claims 1 and 2 wherein the suspensions used for the initial bath contain between 0.1% and 15% of nanometric titanium dioxide.

4. A process as claimed in claim 3 wherein the suspensions contain 1% of titanium dioxide.
5. A process as claimed in claims 1-4 wherein the suspensions contain between 0.005% and 0.5%, preferably 0.05%, of silver.
6. A process as claimed in claims 1-5 wherein said thermal cycle comprises:
- a rising gradient of between 0.1 and 10°C/minute starting from ambient
temperature up to a temperature of between 400° and 850°C;
- maintaining the temperature attained for a period between 30 and 240 minutes;
- free cooling to ambient temperature.
7. A process as claimed in claims 1-6 wherein said suspensions of nanometric
titanium dioxide are obtained by a process comprising the following steps:
i) reacting a titanium alkoxide with a suitable complexing solvent;
ii) distilling the solution derived from step i);
ill) adding water together with said complexing solvent and one or more
polycondensation inhibitors to the solution derived from step it), then heating the
reaction mixture under reflux to obtain the desired nanoparticulate dispersion.
8. A process as claimed in claims 1-6 wherein said suspensions of nanometric
titanium dioxide are obtained by a process comprising the following steps:
- reacting a titanium salt under hot conditions in water in the presence of mineral acids and a non-ionic surfactant;
- possibly reducing the solution thus obtained to a small quantity.

9. metal surfaces coated with nanometric particles of titanium dioxide
using the process claimed in claims 1-8.
10. Metal surfaces as claimed in claim 9 wherein said surfaces are those of
prostheses, or parts thereof, for orthodontic applications.
11. Prostheses, or parts thereof, for orthodontic application, whose surfaces are
coated with nanometric particles of titanium dioxide using the process claimed in
claims 1-8.

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Patent Number

270999

Indian Patent Application Number

4648/CHENP/2008

PG Journal Number

05/2016

Publication Date

29-Jan-2016

Grant Date

29-Jan-2016

Date of Filing

02-Sep-2008

Name of Patentee

COLOROBBIA ITALIA S.p.A

Applicant Address

VIA PIETRAMARINA 53, I-50053 SOVIGLIANA-VINCI,

Inventors:

#	Inventor's Name	Inventor's Address
1	BALDI, GIOVANNI,	VIA TIZZAVOLI, 4, I-50056 MONTESPERTOLI,
2	BITOSSI, MARCO,	VIA BOTTINACCIO, 14, I-50056 MONTELUPO FIORENTINO,
3	BARZANTI, ANDREA,	VIA SAN GIUSEPPE 8, I-50056 MONTELUPO FIORENTINO,

PCT International Classification Number

C23C20/06

PCT International Application Number

PCT/EP07/51030

PCT International Filing date

2007-02-02

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	FI 2006 A 34	2006-02-03	Italy